Remove, change, and fasten Apple Watch bands
support.apple.com
Remove and change bands Hold down the band release button on your Apple Watch. Slide the band across to remove it, then slide the new band in. Never force a band into the slot. If you’re having trouble removing or inserting a band, hold down the band release button again.
Change your Apple Watch band
support.apple.com
Hold down the band release button, then slide the band across to remove it. If the band doesn't slide out, press the band release button again and make sure that you hold it down. Make sure that the text on the band is facing you, then slide the new band in until you feel and hear a click.
How to Change the Band on an Apple Watch - wikiHow
www.wikihow.com
This wikiHow teaches you how to replace your Apple Watch's band with a different one. You can perform this process without any tools or prior expertise. Keep in mind that Apple Watch bands manufactured by Apple will almost always work with your Apple Watch, while third-party bands may not work.