You will need to use an online/offline or offline only donation form.  If you have not already implemented this please use this guide: BB735875

Once your form is configured for offline use:
  1. Select Edit on the donation form.
  2. Go to step 3 Design Donor Screens.
  3. Select Edit on the Donation form.
  4. Select Payment Type.
  5. Save Order and Edit Selected.
  6. Choose Cash and Check as options for the form to be submitted by Admins.