How to change permission of a drive in an external hard disk?

If you want to gain ownership of a drive you can use the chown command:

sudo chown -R username:username /media/username/nameofdrive

This gives the user ownership over the drive without allowing permission to unauthorized users and -R makes this command recursive so that ownership also applies to all of the existing individual files on the drive as well and not just the drive itself.

You can also use -R to make chmod recursive as well.