Unable to delete subnet

Hi

I created and deleted an Integration Service Environments, at point of creating it forced me to create 4x subnets and now I'm unable to delete the subnets.

Here's the message:

• "Failed to delete subnet 'IntegrationServices_3'. Error: Subnet IntegrationServices_3 is in use by//subscriptions/****/providers/Microsoft.ApiManagement/service?vnetResourceGuid=****&subnet=IntegrationServices_3&api-version=2016-07-07 and cannot be deleted. In order to delete the subnet, delete all the resources within the subnet. See aka.ms/deletesubnet."

When I click on the use by link I get:

• "You do not have authorization to access this resource.<br /><br />Resource ID:"

Any idea how I can delete these subnets?

Many Thanks