I have a folder which has a lock emblem on it. When I try to delete the folder, I get a Permission Denied error message.
That lock icon means that you do not have the permission to edit that folder or write anything inside of it.
The reason of this, might be several things.
You are not the owner of that folder. If this is a multi-user desktop, it could belong to some other user, or to the root user. Check the ownership in right click to the folder> Properties> Permissions.
The folder could be read-only. On Linux, folders have 3 bits of permissions, read, write, execute. If the write bit is not set to 1 (True), you are not allowed to edit or write inside that folder. Check the properties in right click to the folder> Properties> Permissions.
If you are the owner of this folder, you can change the permissions to allow writing in to that folder from the same place that you have checked.
If you are not the owner of this folder, and if this is a multi-user setup, ask the owner to have the permission to write. If this is a single user setup, run this command on a terminal to change the ownership of the file (substitute username with your username):
sudo chown username:username /path/to/that/folder
