The working folder C:\Users\.. is already in use by the workspace MININT-F36S5EH;developer1@dynatechconsultancy.com on computer MININT-F36S5EH.

Error: The working folder C:\Users\.. is already in use by the workspace MININT-F36S5EH;developer1@dynatechconsultancy.com on computer MININT-F36S5EH.

Reason: we copied Virtual Machine and created new one. now we tried to map same workspace with different user. 

As server name and folder name is same TFS will not allow to map same folder on same server with different use (As it is logical that, on same server if another user wants to work, he/she needs to create another folder and map with that - TFS does not understand that we have copied VM so this is different server).

Solution: 

Option 1: (Rename developer server)

Rename server but as we know, as D365 FO developer it is not convenient and quick.if you want to go that way refer Microsoft blog - Link

Option 2: (Remove old account mapping)

I deleted my old account workspace by using command prompt.

Open CMD with admin rights, and navigate to C:\Program Files (x86)\Microsoft Visual Studio 14.0\Common7\IDE

prepare command as below.
tf workspace /delete "WORKSPACENAME;PREVIOUSUSERACCOUNT”

copy and paste in the command prompt and hit enter, then select "Y".
tf workspace /delete "MININT-F36S5EH;rahulax@xyz.com"