Edit HERE Collection Items
Choose the collection item you would like to rename either from list or map.
Click "manage" (it is the left one of the two actions, it might be labeled differently in the language you selected, the other one is directions).
A dialog opens. Hover your mouse pointer over the name of your collection item and a small pencil will appear on the name's right hand side.
An editing field will open. You may now rename your collection item.
Click the [Done] button to save your changes. That's it.