First, That's beard.

Second, you can use both.

See the Examples:

I wish he'd shave off that awful beard.

 

I've decided to shave off my beard.

And for face:

Before using the device, you should learn how to shave your face.

First, That's beard.

Second, you can use both.

See the Examples:

I wish he'd shave off that awful beard.

I've decided to shave off my beard.

And for face:

Before using the device, you should learn how to shave your face.