If one of your relationships needs you to delete their contact information from SigParser you can satisfy that request in the following way.
Go to Settings > Admin Settings > Advanced Settings
Scroll down to Scan Rules
If you don't see Scan Rules then you'll need to add a permission to your role to manage Scan Rules.
Add a mailbox scan rule for either an email address or domain name.
When you click Save all the contact data with that email address will be deleted from your SigParser instance.
Warning: Be very careful when using this feature. It can result in large data deletion if you put in the wrong email address.