The following is not exactly what you are looking for, but it will make the current revision an old revision and a copy of an old revision to be the current revision.
1. Open the history tab and select the old revision that you want to be current
2. Right click and select get, let load, and select ok
3. Right click again on the old revision and select open
4. This will open the old revision in inventor
5. Save as the open old revision as a new part ie. current P/N-01 (don't worry this will be deleted later)
6. Close the old revision in inventor
7. Go back to the part in vault and check out and open the current revision in inventor
8. Close this current revision in inventor, but make sure not to check it in (window will appear asking if you want to check in, just click close or cancel and it will let you close the file without checking it in)
9. Go to your os drive and open the P/N-01 in inventor(this is the copy of the old revision that you made in step 5)
10. Save copy as and select the original part number in the OS folder, it will ask if you want to replace the existing part, select ok
11. Close P/N-01
12. Go to your OS folder and open the original part number. It should now look like the old revision (P/N-01)
13. Now you can check in the part and the old revision will now be the current revision in vault. (the second item on the history tab will now be the revision that you wanted removed)
14. Go back to your OS folder and delete the P/N-01
