[A] Unfortunately, we do not have an option to edit an approval rule. but we have a solution for this.
[B] You will first have to delete the previous approval rule. Then you can create a new approval rule with the required changes.
[C] To delete an approval rule, follow these steps:
[D] Go to the "Approval module" (1) and click on "Settings" (2).
[E] Click on the "checkbox" next to the approval rule (3). You can also search for a rule in the search box.
[F] After the rule is selected click on "Remove Rules"(4) The rule will be deleted. Now you can create a new approval rule.
To know how to add approval rule click on the link below -
Keywords: change approval rule, delete approval rule, remove the approval rule