Originally Posted by Demosa
Simple. You cannot change ownership of a file without sudo permissions.
You can change file permissions with chmod, but you cannot change ownership without elevating permissions. It's a security and auditing feature.
EDIT: A few more details as to why. In the old days of UNIX/Linux, when users had a limited amount of space, changing the permissions to 777 and assigning the owner to someone else would let a user have more disk space at the expense of someone else's disk quota. A big deal when you pay by the megabyte for storage. By requiring sudo to change owners, this could be restricted
This I feel is the best suggestion. I do not recommend you fully become root, but instead utilize sudo.
A further point is to observe the group for the file. Many times each individual user has their own named group, typically matching their username. So consider "chgrp" as well.
I very regularly do use things like:
sudo chown -R new-name top-level-directory-name
sudo chgrp -R new-group-name top-level-directory-name