Samsung GALAXY J7 PERX - Memory; Unmount a Microsd Card

Settings 172
Note: Formatting erases all the data on an installed
microSD card, after which the files CANNOT be
retrieved. To prevent the loss of important data, please
check the contents before you format the card.
Unmount a microSD Card
When you need to remove an optional installed
microSD card, you must unmount the card first to
prevent corrupting the data stored on it or damaging
the card.
1. From home, tap Apps > Settings > 
Devicemaintenance.
2. Tap Storage.
3. Tap More options > Storage settings.
4. Under Portable storage, tap your SD card, and then
tap Unmount.
Mount a microSD Card
When you install an optional memory card, it is
automatically mounted (connected to the device) and
prepared for use. However, should you unmount the
card without removing it from the device, you need to
mount it before it can be accessed.
1. From home, tap Apps > Settings > 
Devicemaintenance.
2. Tap Storage.
3. Tap More options > Storage settings.
4. Under Portable storage, tap your SD card, and then
tap Mount.
Memory
Check the amount of available RAM. You can close
background apps and reduce the amount of RAM you
are using to speed up your device.
1. From home, tap Apps > Settings > 
Devicemaintenance.
2. To free up as much RAM as possible, tap Clean now
and follow the prompts.