Can't run sketchup it says active on another computer

You need to ‘Deauthorize’ your ‘machines’
Click on the blue ‘Manage Subscriptions’ button, or sign in on the topright of www.sketchup.com

Once signed in, you can access your TAMP (Trimble Account Management Portal) and look for ‘My Products’
Once you find the right product (SketchUp Pro), you must click on ‘View included Apps’

There, you must look for the right button and confirm.

Note, each version sign in counts as a device

Once you have deauthorized, you still need to sign out in SketchUp and back in, to trigger the changes.