question about mega2560 and flashing grbl

Hello. i'm fairly new to arduino and such and i've written my first program for an x-y mill project that i'm building. I used an uno with it and it works great. I have a new mega2560 that i planned on flashing grbl and making a 3 axis cnc in the future, so i have a lot to figure out.

but i had a question and it's probably stupid. if i upload grbl to the card, and in the future i want to use the card for something else. Is it as simple as uploading a new arduino program, non grbl to the card? and it overwrites all of the grbl code? or would i basically need to erase it and reflash the arduino software back on the card? this is new to me. But i've had times where i had to upload a program onto a usb drive, and to get rid of the program, i basically had to reinstall it's original settings before it acted as a usb drive again.

thanks

It its uploaded via serial (ie, the usb port) - its just anothet sketch.

If you have to upload by connecting an isp programmer to the spi pins, then you would have to connect said isp programmer again and do "burn bootloader" to turn it back into an arduino.

Cool. Thanks. That's what I hoped