uninstall mac software on a mac book pro laptop

Revert your Mac to a previous macOS version

Find an Apple Authorized Service Provider and find one nearest your location. As for Cost - Only Apple could answer that question. We are only Apple Users like yourself.

Backup, create a bootable Catalina USB flash installer and boot it and erase the internal device as APFS and install Catalina to it, restore from the backup.

how does it coast me to replace my Mac book pro 13" battery