Delegations issue

Greetings to all!
I'm having an issue using the built-in feature of delegations. Before anything i have to aclare that i'm using IDM 4.5.6 and i don't have possibilities to upgrade to IDM 4.7 right now so i need to make this work.
The issue i have can be described in this steps:

-Delegation between two users is created with a defined expiration date
-Delegatee sees delegated approval tasks and can approve or deny them.
-Delegation expires.
-Delegatee still sees approval tasks and can approve them

I know there is a feauture that depurates LDAP delegation objects after they expire but i would preffer to conserve them because of compliance.
Does anyone happen to know how to solve this issue?
Thanks in advance.