How to change a thing in Data type B if changes made in Data type A

Hey, So i have Two data types lets say type A and type B, there is a form in the frontend of my website when a user fills a form and submits a entry is created in Data type A. I have added a drop down element in the repeating group (same group where form submitted data is displayed) and this drop down element has 3 options approve, reject, pending. By default its pending now when he admin sets the dropdown value to approved i have set a workflow to create a thing in Data type B till here everything works fine, now when i try to add a workflow for delete a thing when the admin sets the value of dropdown from approved to either pending or rejected its not showing Data type B option under Data sources in To delete action ( To delete is delete a thing action) so how do i achieve this. (I guess its because Data type B is not in the context of workflow im editing as the dropdown element is related to Data type A)

Is there any field linking the two datatypes? If so, you can search for data type b, select the first item then delete it