If you've created a group but don't want to be in charge of it any more, you can transfer the group to another member, or delete the group entirely.
Transferring a group this will give the new admin full permissions and control over the group. You will remain a member of the group but will no longer have special permissions (you'll be relegated to the 'default' role). There is no way to undo this action (unless the person decides to transfer the group back to you) so proceed carefully!
On Web / Desktop
Tap "Transfer Group"
Select the name of the member you want to transfer the group to (note: if the person you want to transfer the group to is not yet a member of the group, invite them to join and once they do, then go through this process)