Can't delete folder - Error 55011

Note - ProjectWise will only allow a folder to be deleted if it has no documents (entries in the database that are typically associated with an actual file) and/or files (the actual dgn, doc, xls, etc.)

Error 55011 usually means that the file does not exist on the server for a document in the folder OR a file exists on the server in that folder but there is no document.

If there are documents in the folder then you will need to do the following with each of the documents:

Open the Properties of the document, under the File section click Advanced. 
Select Remove. 
Click Save (you should see the name of the file go blank and the file size go to zero or blank) 
Click OK. 
You should be able to delete the folder at this point.

If the folder does not have any documents in it, then:

Right click and create an empty document without a file in it to find out the folder Id using a view that shows folder Id.
Go to the server where the storage area is and locate the physical folder dms###### (or d0######) that was named with the folder Id. 
When you are in the folder you should see a file that has not been deleted. 
Delete the file. 
Go back to ProjectWise and attempt to delete the folder from there.