HOW DO I CANCEL THE SPEED DIAL ON A LUCENT 4406D+ I PROGRAMMED IN THE WRONG NUMBER

SOURCE: Speed Dial for a Uniden Model DCT648-3

Do you have a copy of your owners manual? If not, here is a link to a pdf format version of it, from the Uniden website:

http://www.uniden.com/pdf/DCT648-3om.pdf

Speed Dialing
If you store a phone number in a speed dial memory location (10 locations: SPD1 - SPD0),
you can use the speed dialing feature. When the phone is in standby mode, press and hold a
number key (0-9) associated with the speed dial until the phone number appears and then
press talk/flash or speaker. The number stored in the speed dial (SPD1 - SPD0) is dialed.

SOURCE: ge model 28821 series dect 6.0; is there speed dial on it?

does not have speed dial.

SOURCE: Wrong Voice Mail number programmed into Speed Dial "1" Key

You can not remove it; But you can change it

Follow the steps :-
>Menu
 >Messaging
   >Voice Messages
     >Voice Mailbox NO.(CHange it)

SOURCE: uniden power max 5.8 speed dial

Press and hold a number key (0-9) associated with the speed dial until the phone number appears, and then press talk/flash or speaker on the handset or speaker on the base. The number stored in the speed dial is dialed.

SOURCE: Program speed dial buttons

To program a speed dial for an outside line: Pick up the handset, press #00, press the button to be programmed, press *21, then enter the number to be dialed (including any dial out number and areacode).

To program a speaad dial for in internal extension: Pick up the handset, press #00, press the button to be programmed, press *22, then enter the ext to be dialed.

(Once you hit #00, you can also follow the screen prompts).