Want to deactivate T&E (Trip Approvals) workflow for a Personnel number

Hi Team,

We have a requriement to deactivate T&E (Trip Approvals) workflow for a Personnel number, Basically he is a director of the company who doesn't want to and allow his Assitant to do it on his behalf with out him receiving the approval.

Currently we are following the below process

Trip created by Employee --> Checked and Approved by Manager --> If not approved by 5 days, it will go to Manager's Manager (Senior level).

Now for this specific case, we need an exception process as below, where we need to deactivate the Workflow only for Director, if not possible then the trip's Wrokflow can be generated as below.

Trip created by Director -->  Approved by Assistant.

Please guide me.

Regards,

Sandeep