This item usually locked. Choose one of below ways to resolve it.
1) You can using below command to undo the pending changes:
tf undo "file_path" /workspace:workspace_name
2) Or you can just use below command to delete the old workspace
tf workspace /delete /server:your_tfs_server workspace;username
From Visual Studio 2015 GUI:
File -> Source Control -> Advanced -> Workspaces...
In the dialog that came up, check "Show remote workspaces" and the locked workspace came up in the window. Then selected it and click "Remove".
3) Or try to use the free TFS Sidekick application. It has an option to view and undo other user's checkout.
Details about it, please check this blog and more ways to resolve this you can refer the similar question: What do you do if the file in TFS is locked by someone else?