I want to clear out the info on my old iPhone and not delete everything on my new iPhone.

I would like to sell my old iPhone 5 and need to delete the data without deleting it from my new phone.

I backed up my data onto iCloud. The apple instructions on line say to sign out of your new phone from iCloud. however, when i hit sign out i get a message that says "If you sign out of your account, all photo stream photos, docs and data stored in i cloud will be removed from this phone.

Is that what I am supported to do?

And then after i have deleted the other phone, if i sign back in with the new phone will it automatically update my photos, docs, etc?