Find my phone says erase pending when trying to erase another phone

Erase a device in Find My iPhone on iCloud.com - Erase a device in Find My iPhone on iCloud.com - Apple Support

I assume you're doing that?

If the phone is badly damaged then the components required to perform an erase may not be working. for example, it may not be able to connect to Apple's service telling it to erase, so Apple's system think the phone is unavailable and is pending an attempt to contact it.

if its badly damaged or perfectly sound nobody can access it if it has screen passcode. Recycle it or have it repaired without fear.