If you have previously built EOSIO from source and now wish to install the prebuilt binaries, or to build from source again, it is recommended to run the eosio_uninstall.sh script within the eos/scripts folder:
cd ~/eosio/eos
./scripts/eosio_uninstall.shUninstall Dependencies
The uninstall script will also prompt the user to uninstall EOSIO dependencies. This is recommended if installing prebuilt EOSIO binaries or building EOSIO for the first time.