Remove contents of a name lookup field

[heytherejem]

I have a SharePoint list which is populated by users, and one of the fields is a name lookup (linked to our active directory) however I want to delete some of these so the field is blank. The field is not mandatory.

I edit an entry, delete the name in this field, and hit save, and the name still appears. 

I cant even enter 'null' because it wants a name from the active directory. Any idea how I can make this field blank?

Thanks,

Jemma

[#2]

Little confused, could you possibly do a screenshot of what your talking about by chance :)?

[#3]

Sure Chris,

attached is the 'edit' screen on my sharepoint list - it's filled out using a powerapps form. So as you can see there is a name under Aetna Referring Senior - Dicks, Jemma J  and if I remove this so it's blank, and hit OK to save the entry, the name will reappear.

I've tried deleting the anem and inserting a space instead, it just inserts a space and puts the name in again as well.