The problem here likely has to do with the Access Control List (ACL) of the Music folder. The ACL is a separate permission system to the regular POSIX ones that are normally listed by
ls -l. Some other directories in the Home folder and elsewhere also have ACLs.
To see the ACLs within the home directory, use:
/bin/ls -le ~
You will likely see a rule like
0: group:everyone deny delete for the Music directory. As you noted you could override the problem with
sudo. If you don't want to do that (or can't), you have other options, given that you're the owner of the file. You can strip off the offending entry from the Music directory's ACL, based on its index (0 in the example I gave above):
/bin/chmod -a# 0 Music
Or you can strip off all entries in the ACL:
/bin/chmod -N Music
Now you can move the directory around (subject to the regular POSIX permissions). If you want to put the ACL back after the move, you could use:
/bin/chmod +a "group:everyone deny delete" Music_tmp
/bin/ls -le again to confirm the ACL is as you want it. Check out the ACL examples in
man chmod for more info. In particular, this intro is helpful:
Each file has one ACL, containing an ordered list of entries. Each entry refers to a user or group, and grants or denies a set of permissions. In cases where a user and a group exist with the same name, the user/group name can be prefixed with "user:" or "group:" in order to specify the type of name.
I don't think that man page explains the rules around ordering, but this page explains the order rules for ACLs clearly. In particular, an explicit
deny rule will be applied before an explicit
allow rule. So, as long as the
group:everyone deny delete entry is in place, it's not possible to give your user permission to delete with an
allow rule. This is because permission is denied to the
everyone group, which includes you, and that rule will be applied first.