I manage my contacts on my Google account. There is a feature in Google Contacts where one can "hide" selected contacts, as follows. If you go to contacts.google.com, click the three dots to the right of a contact, then click "Hide from contacts" in the menu, the contact will be moved to Other Contacts.
I prefer to keep my digital data organized, and shortening my contacts list will help. However, I'm not sure what the effect of hiding a contact is (other than it not displaying in the contacts list on a contacts app).
We're talking about a contact that I'm not likely to communicate with in the future, but it would still be better for me to save their details, for example in the unlikely event that they phone me. If a hidden contact phones me (on my Samsung Galaxy S8), will my stock phone app show me who is calling?