To (permanently) remove a project or solution from source control
1. In Visual Studio, click File, click Source Control, and then click Change Source Control.
2. In the Change Source Control dialog box, select the project and/or solution you want to remove from source control, and then click Unbind.
3. Delete all solution or project files in the source control database.
4. In Windows Explorer, locate the working directory for your solution/project and then delete all *.scc files.
Note In Visual SourceSafe and many other SCC systems, if other users have checked out the solution/project in the past, even if they have since checked in their changes, the next time they attempt to Get or Check Out the solution/project, they will be prompted to add the items to source control from their working copies on disk. On the SourceSafe team, we call this a “pending add“, which is a little confusing. Anyway, if you want to guarantee that a solution/project is permanently, permanently, permanently removed from source control and will never again re-appear in your database, you should repeat the final step in the preceding procedure for all solution/project enlistees.
To NON-permanently remove a project or solution from source control in Visual Studio, do not complete the final step in the preceding procedure.
I don’t know why such a simple task have such a complicated solution with Microsoft 🙁