Savings bonds issued after June 2003 have a term of 20 years, and there's no law preventing you from selling or buying bonds after they are issued, so the U.S. Treasury has forms to reissue the bonds with the new owner's name on them. You can obtain the necessary form to change the ownership from the U.S. Treasury's website.
Which form you use depends on whether the original owner died, you're moving the savings bond to a personal trust or it's simply a new owner. If the old owner died, use Form PD F 4000 if the new owner is named on the bond or Form PD F 5336 if there's no new owner named. If you're moving the bonds to a personal trust, use Form PD F 1851. If you're simply changing the owner, such as if you bought the bond from another owner or received it as a gift, use Form PD F 4000.