To Retire Design History

Select File > Settings > Configuration > Configuration Variables .
Select the MS_DESIGN_HISTORY configuration variable.
Click Edit.
The Edit Configuration Variable dialog opens.
In the New Value field, type retire=1.
Click OK, then click OK again to close the Configuration Variables dialog.
Verify that you want to save changes to the user configuration file.
Exit and restart the application.
Select Drawing > Utilities > Design History > Retire .

The Choose Revisions dialog opens.
Select the revision number.
Design history will be deleted from this selected revision number back through the start of the history.
Click OK and then Yes to confirm the revisions that are to be deleted.