Rule 5. Locking.

yes, but you're likely destroy it in the process. bite valves are not designed to be cleanable or fixable, but rather replaceable.

buy a new one. and yeah if it's too old, they won't make new ones, so time for a new bladder.

I've broken every bite valve I tried to fix.

I'm not familiar with this one specifically, but the valve I have comes apart just above the twist part. It took some force but there was no mechanism keeping it on. You might want to see if you can find a manual from the manufacturer as well.

You can’t take it fully apart but it should be relatively easy to remove the silicone bitey part. Those are often replaceable, and with it removed you should be able to get a straw cleaner in there and mostly clean and dry it. Expect that there’s a lip so you’ll have to do a little prying and pulling. It should go back on just as easily (or not) as it comes off.

It looks like it's just a pressure fitting, so I'd get a dull edge like a credit card or the back of a butter knife and try to gently work it up from where it touches the plastic.

Don't pull on it, though.

Like others have said, it's not meant to come apart. That being said, it went together, so there is likely a way to get it apart. Unless it was press fitted.

I don't think you can disassemble that.

If you have a source of compressed air, you could try blowing out whatever is inside, then soak it in bleach, alcohol, or other disinfectant to get kill the bacteria.

how bad was it bitten?