You can do this manually or with a third-party app, as below.
Here’s a list of extensions that Apple suggests looking for:
Click the Uninstall button to the right to get rid of the suspicious extension. In Safari, head into the Preferences, click on the Extensions icon in the top row and then the extension you want to uninstall on the left.
Uncheck the “Enabled” checkbox near any extension you don’t recognize, or delete it completely by clicking on the trash can icon to the far right.
In Chrome, go to the Settings menu again and click on Extensions. Disable or delete Chrome extensions here.
