A sub-process has a start form, I need to remove input from that form so I can p

Configure the Assignment of the sub process to be Automatic (i.e. start as process designer or initiator) and you should have the option to map the two.

I tried that, it did not work.

I am not sure I completely understand, so I apologize if this is a bit off. Any additional info you have would be helpful. Hope this helps a bit....
Any field you want to pass in needs to be marked as parameterized
Check the start form to make sure the field is there, but don't remove, etc...
From the subprocess node, refresh the data after any change and make sure mappings are good
Make the subprocess node unassigned and run as designer or initiator (based on security)
If the user then needs to input values, have them fill out a user input task

I have two processes (A and B). B is sub-process and has few existing parameters to be passed from parent Process A. I added new input parameters to B. In A, there is a start form on sub-process node (B) and it is assigned a user. After adding new parameter to B, I refreshed sub-process node in A, but I can't pass value to new input parameter, it says from form, but I still can pass value to existing input parameters.