There is a way on the TI-84, not sure if the this works on a TI-83, but it should be the same.
Go to 2nd "mem" (the '+' key),
then go down to GROUP. Press enter on it,
then go to "Create New" then choose a name that you can identify it by.
Then, go to Prgm…
and choose the program(s) that you need to hide.
Press enter on the programs that you want hide, so that it selects it.
Then go to DONE, hit enter.
the programs that you chose are now backed up
To "hide" a program, delete the program from 2nd "mem", mem management, prgm…, then press delete on the program you want to hide. say Yes, I'm sure.
If you look in your programs, the one you hid is gone. :D
To get it back!
Go back to Group under 2nd mem group
go to UNGROUP
ungroup the group that you made earlier
TA DA your program is back.
Thgis method is also a good way to back up a program before you change it so that you dont make a really big mistake and cant change it back.