This article explains how to remove an SD card from a MacBook.
How to Remove an SD Card from Your MacBook SuperDrive?
There are three ways to safely remove an SD card from a MacBook. They all perform the same task, which is to disconnect the drive before physically removing it. This is called ejecting, although it is different than physically ejecting the card. You must eject the card through macOS before you can physically remove or eject it from your card reader.
The easiest way to safely eject an SD card from a MacBook is directly from the desktop:
Locate the SD card on your desktop, hold down Control and then click the SD card icon.