Laptop fan (ventilator, blower) Does not Stop?

It sounds as though the heatsink and fans may be clogged with dust

As a temporary measure you can buy a laptop cooling tray that you sit the laptop on. This contains fans and encourage airflow into the laptop cooling vents

You can try clearing it with a can of compressed air you can buy from any computer store, by blowing back through the vents but if that doesn't work the laptop usually has to be stripped to gain better access. This is not normally a DIY job unless you have done this before. Sometimes the heat sink and fans are easily accessible after removing a cover, other times the motherboard has to be removed which involves a complete stripdown

May be have a look on youtube for a disassembly video for your model so you can see what is involved

the fans on laptops are essential for cooling. Without them, the laptop will shut down constantly from overheating and potentially damage components. Try elevating the laptop/using it in a place with more air flow. If it is very noisy all the time, the fans could be dirty or faulty

Are you gaming? Do you use a cooler base?

A laptop fan when working under normal conditions, cannot be heard. It speeds up when the unit overheats.

If you slow it down or stop it, you are likely to overheat the cpu, which could destroy the machine.