I NEED HELP!!!!!!!!!

[puff]

i just got my first iMac, it was my grandfathers but when he passed away it was given to me....anyway...i have no cd's, nor do i have the main passwords...i only have one password to one profile....not the main profile...how do i delete everything..and start over with new profiles...and everything......
help me please
thank you

 

[marker227]

you need softwear disk's

 

[abhishekit]

which OS are you running?

 

[puff]

os x

g4 status