How To Delete A Workflow Process In ProjectLink R7.0? 
There is no UI to delete a single workflow instance. 

The command line utility, 

windchill wt.clients.workflow.engine.DeleteWfProcesses

can be used to delete a set of workflow processes in a specific state. 

Alternatively a custom tool can be written using the API on StandardWfEngineService 
to delete a single process. void deleteProcess(WfProcess process) Deletes process 
passed as argument

=============

The workflow process priority does not match the priority defined in the START-WORKFLOW webject.
The workflow process priority does not match the priority defined in the START-WORKFLOW webject. 

This issue can be witnessed under the following scenario : 

1. Create the webject, which could be something as 

<ie:webject name="startworkflow" type="grp"> 

<ie:param name="instance" data="com.ptc.ptcnet.ja2k-wnc-70.Windchill"/>
<ie:param name="object_ref" data="VR:wt.part.WTPart:30442:014663874-1076251564453-28286616-141-226-168-192@ja2k-wnc-70.ptcnet.ptc.com"/> 
<ie:param name="template_name" data="Submit"/> 
<ie:param name="PRIORITY" data="HIGHEST"/> 
<ie:param name="group_out" data="out"/> 
</ie:webject> 

2. Run this webject with jsp file on browser 

3. Goto worklist and you can find the workflow process is not correct 

4. Modify 

<ie:param name="PRIORITY" data="HIGHEST"/> to HIGH, NORMAL, LOW and LOWEST and then restart servlet 

5. Run the jsp with browser again 

6. You can find the workflow priority is not correct 

=============

To Reproduce: 
>> Create a WfProcessTemplate with start --> AdHoc Default Activity --> end 
>> Initiate the workflow 
>> In adHoc workitem, create a single adHoc activity 
>> In wcExplorer (/System/Workflows/Running), 
delete the WfProcess instance 


Resulting StackTrace: 

wt.workflow.TableLoaderAction.setupTableItem: 
wt.util.WTRuntimeException: 

Exception in getCachedObject; nested exception is: (wt.fc.fcResource/32) wt.fc.ObjectNoLongerExistsException: 
Cannot restore "wt.workflow.engine.WfBlock.151830" because it no longer exists. 
at wt.fc.StandardPersistenceManager.restore(StandardPersistenceManager.java:2248) 
at wt.fc.StandardPersistenceManager.restore(StandardPersistenceManager.java:2195) 
at wt.fc.cache.StandardObjReferenceCacheService.getCachedObject(StandardObjReferenceCacheService.java:555) 
at wt.fc.cache.StandardObjReferenceCacheService.getObject(StandardObjReferenceCacheService.java:303) 
at wt.fc.cache.ObjectReferenceCacheFwd.getObject(ObjectReferenceCacheFwd.java:82) 
at wt.fc.CachedObjectReference.getObject(CachedObjectReference.java:388) 
at wt.workflow.engine.WfActivity.getParentProcess(WfActivity.java:1255) 
at wt.workflow.work.WorkItem.getIdentity(WorkItem.java:1297) 
at wt.identity.DisplayIdentificationPersistableDelegate.initializeIdentifier(DisplayIdentificationPersistableDelegate.java:210) 
at wt.identity.DisplayIdentificationStandardDelegate.initialize(DisplayIdentificationStandardDelegate.java:360) 
at wt.identity.IdentityFactory.getDisplayIdentityDelegate(IdentityFactory.java:354) 
at wt.identity.IdentityFactory.getDisplayIdentity(IdentityFactory.java:227) 
at wt.htmlutil.HtmlUtil.createTrailObjId(HtmlUtil.java:1231) 
at wt.htmlutil.HtmlUtil.createTrailId(HtmlUtil.java:1372) 
at wt.workflow.worklist.SelectWorkItemCheckbox.getValue(SelectWorkItemCheckbox.java:75) 
at java.lang.reflect.Method.invoke(Native Method) 
at wt.workflow.TableLoaderAction.setupTableItem(TableLoaderAction.java:557) 
at wt.workflow.TableLoaderAction.loadTableItems(TableLoaderAction.java:486) 
at wt.workflow.TableLoaderAction.loadTableItems(TableLoaderAction.java:157) 
at wt.workflow.TableLoaderAction.loadTableItems(TableLoaderAction.java:139) 
at wt.workflow.worklist.UserLoadAction.actionPerformed(UserLoadAction.java:60) 
at wt.clients.util.ActionLoader.actionPerformed(ActionLoader.java:277) 
at wt.workflow.worklist.WfWorkListProcessor.createWorkListModel(WfWorkListProcessor.java:884) 
at wt.workflow.worklist.WfWorkListProcessor.getModel(WfWorkListProcessor.java:529) 
at wt.workflow.TableTemplateProcessor.tableItems(TableTemplateProcessor.java:96) 
at java.lang.reflect.Method.invoke(Native Method) 
at wt.htmlutil.MethodAction.action(MethodAction.java:133) 
at wt.htmlutil.CachedHTMLTemplate.execute(CachedHTMLTemplate.java:144) 
at wt.htmlutil.CachedHTMLTemplate.execute(CachedHTMLTemplate.java:120) 
at wt.htmlutil.HTMLTemplate.process(HTMLTemplate.java:206) 
at wt.templateutil.processor.GenerateFormProcessor.handleRequest(GenerateFormProcessor.java:413) 
at wt.enterprise.URLProcessor.URLTemplateAction(URLProcessor.java:359) 
at java.lang.reflect.Method.invoke(Native Method) 
at wt.httpgw.HTTPResponseImpl.writeExternal(HTTPResponseImpl.java:311) 
at java.io.ObjectOutputStream.outputObject(ObjectOutputStream.java:1172) 
at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:366) 
at wt.method.MethodResultWriter.writeExternal(MethodResultWriter.java:154) 
at wt.method.MethodResult.writeExternal(MethodResult.java:202) 
at java.io.ObjectOutputStream.outputObject(ObjectOutputStream.java:1172) 
at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:366) 
at sun.rmi.server.UnicastRef.marshalValue(UnicastRef.java:268) 
at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:251) 
at sun.rmi.transport.Transport$1.run(Transport.java:152) 
at java.security.AccessController.doPrivileged(Native Method) 
at sun.rmi.transport.Transport.serviceCall(Transport.java:148) 
at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:465) 
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:706) 
at java.lang.Thread.run(Thread.java:484)