there are two ways,
1) download default.ccf to your remote with PE
2) make a small change to the CCF on the Pronto (i.e. change a label, learn a code, delete a button....) and then go into the remotes setup and press the revert button. revert only works on a CCF that was modified on the Pronto and it will bring you back to the default (i.e. it is not an undo)