Erase hard drive on old MacBook
I have an old MacBook & want to erase drive before donating
MacBook Pro 13″, macOS 10.15
Here is What to do before you sell, give away, or trade in your Mac - Apple Support — review all the steps there, including step 7.
If that sequence is not working, please indicate what you’ve tried, and what did (or did not) happen, and what diagnostics were shown if any.