You can delete a drawing revision by going to Drawings > Drawing Sets.

1. From the home page, under Projects, select the name of the project you want to open.
   Alternatively, go to the main menu in the upper left-hand corner, select Projects, and then select the name of the project you want to open.
   The Dashboard for the project appears.
2. Click the Drawings tab.
3. From the Drawings tab, select Drawing Sets.
4. Under Set Name, select the drawing set with revisions you want to delete.
   The drawing set appears.
5. Select the check boxes next to the drawing revision(s) you want to delete.
6. Click the Actions button and select Delete Revisions
7. Confirm the deletion by clicking Confirm.