Texas Instruments TI-83 PLUS - Manual (Page 344)

TI-83 Plus Statistics 341
Editing an Element of a Formula-Generated List
As described above, one way to detach a formula from a list name is to
edit an element of the list to which the formula is attached. The
TI-83 Plus protects against inadvertently detaching the formula from the
list name by editing an element of the formula-generated list.
Because of the protection feature, you must press Í before you can
edit an element of a formula-generated list.
The protection feature does not allow you to delete an element of a list to
which a formula is attached. To delete an element of a list to which a
formula is attached, you must first detach the formula in any of the ways
described above.