How do i remove or change the phone number i submit to have im sent to when i am off line?

i was add a phone number to my im so that when i am of line i will have my im's sent to the phone but the phone number i i gave i would like to change but i cant find the option to change it can you tell me how to do thisHow do i remove or change the phone number i submit to have im sent to when i am off line?
Go to your personal account information or click on the little blue help in the upper right corner of your screen in yahoo. good luck!