Hi Maria,
There is no explicit sort option.
In SE43, provide the Area Menu name and get into the change mode.
In the next screen, expand the folders that you wanted to be sorted.
Say your list of T-codes looks like below.
ABC
FGC
DBA
And now this has to be sorted as
ABC
DBA
FGC.
Now place cursor on a T-code (DBA) and click on 
(Select/Deselect) button. This will highlight the T-code DBA and then place cursor on the T-code ABC and click on 
(Reassign) button and save.
PS - Assignment should be done at the 'same level'.
Now, you T-code list will be sorted and this has to be performed several times to sort the entire list.
Regards,
Hima