Hey,
The error you got because you might have installed derby database and tried run that statement again. So you do one thing, inside your hive directory you will get a directory that is metastore_db. Remove it with the help of this command:
rm -rf metastore_db/
And again try to reinstall derby database with the command:
schematool -initSchema -dbType derby
I hope it will help and the error will go.