Remove pending invite - design needed

[bentateart]

When an admin clicks the link to remove a pending invite, the confirmation is a default browser alert.

URL:

https://managing-registers-staging.cloudapps.digital/admin

Steps to recreate:

1. Login as an admin
2. Click 'Manage admin team'
3. Invite a new admin user
4. Click 'Remove invite' on the 'Admin team' page

Expected result:

Not sure

Actual result:

[elliecraven]

for next iteration - not a condition of this release