How do you remove write protection in card reader?

1. The memory stick may have an actual physical switch to enable and disable write protection. Mine slid forward and back, very much like on a 3 1/2" floppy disk.

2. If your flash drive works fine at home and not at work it is likely your IT people have set security policies to prevent their use. This is to prevent people from copying company files and taking them somewhere.

3. If your flash drive is prepared ("formatted") to run in Windows and you put it in an Apple it will appear to be read-only, and vice versa. There is only one way to prepare a drive to be used on both systems simultaneously: it is called FAT (specifically FAT32.) Be aware FAT32 is old and you may run into its limitations.