Epson U11, U12 or switch so they are

On a 3.5-inch diskette, the write-protect device is a small switch on the back of the diskette in the lower right comer, shown below. To write-protect a 3.5-inch diskette, slide the switch toward the edge of the diskette until it clicks into position, exposing a hole in the comer.

switch

To remove the write protection, slide the switch toward the center of the diskette until it clicks into position and the hole is covered.

or switch so they are

Using Your Computer 1-13