Hello, is it better to remove a tooth or do nerves killing instead? thank you!

Best to keep tooth: Usually, it is better to keep your tooth with root canal therapy than to have it extracted. Your teeth can shift, drift, and tip if other teeth are missing. Your whole mouth, and bite can change with a missing tooth. However, some teeth must be extracted if they are non restorable. Then replacement teeth can be placed.

Keep the tooth: By "nerve killing" i presume you mean root canal. If it is an option it is much better to have a root canal and restoration done then to remove the tooth. Keeping a functional tooth with a root canal is much better for your ability to chew than an empty spot, a fake tooth, or a denture.

Extract\last resort: It is almost always better to save teeth, although there are some exceptions. In order to answer your question properly and accurately, we would need to know a lot more information. Please ask your dentist to fully explain all treatment options, the pros and cons of each, and long term prognosis to try to save that tooth. Only then can you make an intelligent decision and the right choice.