Hi Kastara, my name is Neil, I'm an independent adviser and a Windows 10 user like you.
Sorry you're having this problem with your power supply / battery on your laptop.
As a possible fix, with your laptop turned off, unplug the charging cable from the laptop and then remove the battery from the laptop and leave it out for at least 5 minutes. During this time, open your laptop and press and hold the power button for 10 seconds. This will eliminate any remaining charge held by your laptops components.
Afterwards, plug your battery back in, plug the charging cable back in, and then turn your laptop back on and see if it charges normally. Give it some time to charge. Then remove the charging cable and see if your laptop remains on, or if it still powers off.
If your laptop turns off immediately when you unplug it from a power source, it means your battery is not working. Most likely, your battery has reached the end of its useful life and has stopped holding a charge.
Sometimes, laptop batteries can stop working out of the blue. This can happen if there is a short circuit in the internal components of the battery. While most batteries are pretty rugged, extreme heat or cold, contact with liquid, or a sharp jolt from bumping or dropping your laptop can damage the battery.
Another possibility is that the battery connector inside your laptop is damaged. This can happen for the same reasons the battery itself might get damaged.
If it doesn't hold a charge anymore and your laptop is still within the warranty period I would contact your laptops manufacturer and claim on your warranty. If it is outside of warranty repair then you might want to purchase a replacement battery. You should be able to do this from your laptop's manufacturer, or you can find cheaper, suitable replacements on Amazon or eBay.
In the meantime, although you won't overcharge your battery by leaving it in your laptop, you should be able to use your laptop without the battery being plugged in if this bothers you. Just remember that your laptop will instantly shut down the moment it is unplugged from the power source.
I hope this answers your question. Let me know if you need more help.