After searching google, I found this removal method, but the length won't allow me to copy it here without creating lengthy posts, so I give you the hyperlink instead
http://www.simprograms.com/?p=658
Another one (this one is official but much less detailed)
http://www.securom.com/support_faq.asp --- Q36
Please note that I have NOT personally tried out any securom removal tool before, since my securom protected game works fine for me so far. You may try this out through. You are also adviced to backup any important information before doing so - I don't know whether any problem will emerge as you remove Securom! Take this as a discriminar!
P.S. The Securom will be reinstalled again once you play a securom embedded game which is not yet cracked / patched to remove protection, like SH4 v1.4