Q: how do i disconnect sd card from my mac book pro

How do I remove a card from the SD card slot?

As with any removable media device, allow any data transfer to SD media to complete before removing the card. When removing the card, the best way to insure the integrity of your data is to drag the icon that represents the card to the Trash, then remove the card from the slot after the icon disappears from your desktop.

http://support.apple.com/kb/HT3553#13

u can eject the mounted sd card and then remove from ur mac