Hi!
I do not know if there is a formal, CA-approved certification associated with the Layer 7 / APIM products. I know that some partner orgs were managing certifications and trainings, and I know that we have some online resources you can review.
We do have some online training available, which may be accessible here if the link works:
CA Technologies Global Search Results
If that link does not work, go to the Course catalog search page and search against the product "API Management" to view the full list of currently available online courses. This is a good place to start.
CA Technologies Global Search Results
There are also some dated but still useful videos on youtube that you can use to get started with the Layer 7 /APIM products.
CA API Management - YouTube
If you want to know more about Live API Creator (a product that also falls under the APIM umbrella) you can download a free trial and view the many videos and online training materials over on the Live API Creator website.
CA Live API Creator
Welcome to CA Live API Creator on Vimeo
Cheers,
-case-