I am unable to view forms created by my sub account user.

I have set up a sub account user, who has created and tested a form. I am unable to view the form. How do I do this please?

If the sub-user created the form within his account, you will not be able to see the form, unless he shares the form with you, by adding you as a sub-user under his account: https://www.jotform.com/help/232-How-to-Share-Forms-with-a-Sub-Account-User 

Please note that the sub-user feature is not meant to inherit account benefits, it is only meant to share forms with someone else.

However, the sub-user can transfer his forms to your account, and in that way, the forms will belong to you, and they will be subject to your account benefits: https://www.jotform.com/help/342-How-to-transfer-or-share-forms-and-data-with-another-account