Old Incoterm Deletion

Hi

There are few incoterms in our system, with these Inco terms , there are orders created till 2008 , afterwards we have not been using these incoterms to create sales orders and in future also we don’t use them . Some reason, sales orders haven’t been archived in our system.

Question is , if I delete these incoterms from system whether it creates any problem in our system ? I need to delete these incoterms as users are getting confused.

Thanks in advance