Given that the Richardson Maturity Model is based on REST, and the urls you provide are not RESTful, they don't classify as any one of the 4 levels.
It is not RESTful to put a verb in an url. (see http://www.restapitutorial.com/lessons/restfulresourcenaming.html)
The HTTP verbs that are mentioned in the link you posted are PUT, POST, GET, etc. HTTP verbs are not related to the actual url they operate on.
A RESTful version of
http://aaa.com/api/clients/UpdateClient would be
UpdateClient would translate to
PUT http://aaa.com/api/clients/1 HTTP/1.1
Where a new (updated) resource is provided, to replace an existing one (client 1 in this case)
RemoveClient would translate to
DELETE http://aaa.com/api/clients/1 HTTP/1.1
DELETE and PUT as shown here are the HTTP verbs that are discussed in the link you provide.