I am not responsible for any damage caused by you following this!
I put that disclaimer, but I did test it myself just to be sure
In phpMyAdmin, under your vBulletin database, look for the table "user".
This shows you all sorts of information, including the "lastactivity". This is based on Unix time, for example on my users table last activity, the first date I see is: 1380060934, which is 9/24/13 5:15:34pm EST
You can choose a date that you would like to remove users before, you wanted 100 days ago, which is June 17, 2013 ( Add/subtract Dates Here )
Now to delete the users before that timestamp should look something like:
Code:
DELETE FROM user WHERE lastactivity < '1371445200'
Thank you , it works without problem. Its really helpfull query specially when alot of spammer need to be remove. From admincp it was easy if number of members are less. But now its good.