This is a tablet, but you posted in the laptop forum.
To do as you are wanting to, alas is not possible on your device. The tablet would have to be running Android "Marshmallow". As far as I know your is only updatable to "KitKat". If you could find a way to update to "Marshmallow" then you may be able to turn the SD card as "Internal" storage rather than the standard "External" storage, but that is not guaranteed. Some devices cannot make the change, no matter the OS they are using.
If you can get it to run "Marshmallow" and can get it to allow the change, then you will need to start with a blank SD card. This is because when it is converted, formatted and encoded, anything already on it will be wiped.
How to turn external SD card into internal storage on "Marshmallow".
1. Go to device “Settings”, then select “Storage”.
2. Select your "SD Card", then tap the “three-dot menu“ (top-right), now select “Settings” from in there.
3. Now select “Format as internal”, and then “Erase & Format”.
4. Your SD Card will now be formatted as internal storage.
5. Reboot your tablet.
NOTE: If you don't reboot the tablet, many things may not work correctly, so make sure you do.