Step 1: Hop to the Payables Tab.
Step 2: On the right, click Approval Rules.
Step 3: Corresponding to the Payable Approvers Box, click the three dots.
Step 4: Select the individuals who need to be able to approve a payable by check marking the box on the left next to their name. Uncheck those you no longer wish to be approvers.
Step 5: Select Save Approvers.