Can I take my Laptop battery out...

They say it's better not to use your laptop while it's charging because it ruins the battery, but I do it anyways.

Some computer manufacturers provide support apps. Asus does and it recommends for battery life, to charge to 60% and no higher and provides a program that will do that.

If you think about it, everytime you use your computer it will keep the battery charged at that percentage. Now if you have your battery constantly at 100% everytime you use the computer the battery will lose a bit of power and then have to recharge to 100%. At least with 60% it does not have to do that as many times.

This is also why phones shouldn't be charged overnight, because once they are fully charged, they'll start losing a little charge and then recharge to that 100%, and lose a little charge and so on, wearing out the battery faster.

If power goes down and you are not able to shut down properly you can damage many operating system files and your data files that you were working on at that time.

Although in such event there are ways you can restore the operating system files but the procedure may not be the simple. For your other data files, some apps provide ways to restore your last saved file, and some even retrieve your data after you last saved it but that is not a certainty. Moreover if you have Hard Disk Drive you can damage the data completely in such cases as this can lead to bad sectors in your drive which makes data completely unreadable. If you are using a could apps to save a run your data like Google Workspace, then you are on safer side in respect to your data.

Note: SSD drives are more reliable in such cases in comparison to HDD.

If you are sure that the power in your area is stable and will not go down without prior intimations, you can consider that option.

Your laptop must be pretty old if you can take the batteries out.

Batteries do tend to die with use. The average laptop battery will last ~2 years before it needs replacement.

Over what period of time? Batteries all eventually get old and can't be charged.

I always use my laptop plugged in because it loses charge really fast

Personally I haven't really noticed any particular method working better than another. With modern lithium ion batteries it is not as big of a deal as older battery tech. And for me as long as I can keep getting replacement batteries online for my Thinkpads I am not too worried.

I kept the laptop battery in and used with the power in. I think my battery lasted longer cause.. maybe diff with diff techs

I use to have a cell phone the battery quit working. It only work with the phone plugged in