Unmounting the SD card
To remove your memory card from your device, go to your device's Settings then tap on Storage (or SD card and phone storage) > and tap Unmount SD card.
The phone will stop communicating or transferring information from the memory card to the device, or vice versa from the phone to the memory card, and allow you to remove your memory card safely.
If you do not unmount your SD card or power off the phone before removing your memory card, you can corrupt any files transferring during removal.
You can also run the risk of damaging the SD card.