Western Digital Passport for Macbook Pro running Monterey

Welcome to the Apple Support Communities.

1. Go to Disk Utility (Finder > Go > Utilities).
2. In Disk Utility, select "View" > "Show All Devices". Select the the name of the external drive that is at the top of the hierarchy. Its name will end in "Media".
3. Click Erase, and make sure the information matches:
   1. Name: any name you want
   2. Format: APFS
   3. Scheme: GUID 
4. Click erase, and Back up your Mac with Time Machine - Apple Support.

Cheers,

Jack