Click on "Initialize..."
or if the useer your login with can adminastrat the computer then try adding "sudo " and entering your password when prompted.
So:
sudo diskutil eraseVolume HFS+ PenDrive disk2
Click on "Initialize..."
or if the useer your login with can adminastrat the computer then try adding "sudo " and entering your password when prompted.
So:
sudo diskutil eraseVolume HFS+ PenDrive disk2