I would like to give edit access to my employees for the letters. Is this possible?

Yes. You can provide edit access to your employees by performing the following actions: 

1. 1. Login to greytHR Admin Portal. 
   2. Navigate to Employee > Setup > Letter Template. 
   3. Click +New Letter Template if you want to give edit access for a new letter template. Click the Edit Template icon of any existing template if you want to give edit access for an existing letter template. Step 1: General Information page opens.
   4. Go to Custom Fields. Select the Field Name, Field Label, Type, Required, List Values as per the requirements. Under Allow Employee Edit, select the check box. Selecting this check box gives edit access to the employees.