Core Contracts

Summary

It is not possible to removed fully remove the allowance given to an account, it is possible to reduce to 1 wei but not to zero.

The function implements a sanitzation check to ensure allowance cannot be zero:

Some of the reasons to remove an allowance could be:

1. The spender takes too much time to use it: leaving an allowance floating around it is not good management of the funds of the protocol

2. The spender becomes a known exploiter

3. Given by mistake to the wrong account

Recommendations

Remove the check and allow to remove the allowance.