The "member ranking" or "member title" is merely set by the number of posts a member has made.

See the section in the FAQ section:

Member "titles"

The "star ranking" is embarrassing and I wish it was easy to remove. It is voted on my any member, from one to five stars. I BELIEVE it also reduces over time according to the number of posts members make or is maintained if some level of number of posts is maintained. I really have no idea. Some members have had five stars but dropped for no apparent reason over time. So I believe now the software itself may reduce them over time.

Myself I sometimes votes members "stars" but only ever do 5 stars (after a great post or whatever). It is petty IMO to do anything else.

As I said I find them embarrassing and would like them done away with in total.