You don't have to delete anything.
You just need to download the new app and it will overwrite the old one.
Just make sure your device is in programming mode. If you are using our tag board, this means to have the right switch settings and push the reset button.
The documentation in the SDK has pretty good explanation as to how you can program the TAG.
You would only have to recover if something went wrong on the last download and the chip isn't responding.