how do i remove an AGENTS details from my profile?

'Representation' is a section on the separate Resume page, not a section in the main database. Unless there is an orange asterisk (*) beside the data on your page, the data is from the main database. If you are Jon Campling, then the Agent shown on your Pro page has no such asterisk, while your Direct Contact information does.

This request to delete this information can be submitted from any IMDb Pro Account.

You need to start on your main Pro Name page.

Click the  Edit Page button near the bottom of the page.

Select Correct / Delete from the dropdown menu beside Representation: I know the company and (optionally) the agent  (first item in the Contact Details  group).
Click Continue (at the bottom of the page)

Change Keep: to Delete in the Action column beside the credit.
Click Check these updates

Enter the Explanation  in the box the item. This is critical. I recommend something like :

I am Jon Campling. I am no longer represented by this agency, so I am removing it from my page.

Click Re-check these updates

The background of the item should now be green and you should be able to  Submit these updates

This should be done in a couple of days, but can take up to 2 weeks.

P.S. You might want to consider moving your Direct Contact information from your Resume to the main database, since your Resume can be seen by any IMDb user, while the Contact information in the actual database is only available to those who have paid for IMDb Pro.