Use the "Deauthorize All" option and then authorize any computers (iPhones/iPads are not affected) that you still have and want to use.
See the following from Authorize or deauthorize your computer for iTunes Store purchases - Apple Support
If you need to deauthorize a computer that you don't have access to
To deauthorize a computer that you don't have access to, you have to deauthorize all of your computers. Then authorize each computer that you have again. You can deauthorize all computers only once a year.
- Open the Apple Music app or Apple TV app.
- Choose Account > Account Settings.
- Sign in with your Apple ID and password. Forgot your Apple ID?
- At the top of your Account Information page, go to the Apple ID Summary section.
- Next to Computer Authorizations, click Deauthorize All.
- Authorize each computer that you use again.