Cancel call forwarding

Excellent, glad you found the star code for that. If it helps, call routing can also be changed via a menu setting on Samsung Galaxy devices. Here is some guidance of you prefer this approach (screenshots included for illustration) :

Within the Samsung Phone app (i.e., the "dialer"), open the overflow menu in the upper right and select "Settings".

Select "Supplementary services" (note, this may take a few seconds and might display an error before the setting opens normally).

Select "Call forwarding"

Modify each setting as you require. The "when unreachable" option might prove helpful if your coverage drops (e.g., indoors) and you have a secondary number as a "failover" option.

(Note: these settings may differ depending on your mobile carrier and software version. All call routing settings can still be changed using the star codes specific to your mobile carrier.)

I hope this helps.