Renaming an existing user

Hi,

I've a scenario of 10 users whose initial email address was example1@domain.com (up to example10), they use email + OneDrive.

Recently, I'm asked to rename all 10 users from example1@domain.com to location1@domain.com and so on...

My questions...

1. How can we rename an existing user?

2. Tons of files were shared in their OneDrive, rename would have any adverse effect on OneDrive?

Thanks in advance.