There is no straightforward way to remove all the information of a project from the SVN repository and retrieve that diskspace. The only way to achieve this:
- Dump the repository to a dumpfile.
$ svnadmin dump C:\Foo_Rep > C:\foo_rep_dump
- Filter out the project you want to remove from the dumpfile.
$ svndumpfilter exclude Project_to_del < C:\foo_rep_dump > C:\foo_rep_dump_updated
If you have many projects that you want to remove, repeat this step for each of them.
- Create a new repository.
$ svnadmin create C:\Foo_rep_new
- Load the updated dumpfile to new repository.
$ svnadmin load C:\Foo_rep_new < C:\foo_rep_dump_updated