Can i Install Mac Os Mojave?

You can not install a macOS older than what the machine shipped with new.

Revert your Mac to a previous macOS version - Apple Support

How to erase a disk for Mac - https://support.apple.com/en-us/HT208496

How to reinstall macOS from macOS Recovery - https://support.apple.com/en-us/HT204904

According to Everymac.com, that Mac shipped with 10.14.5, so you should be able to install Mojave.