People do really get us upset to the extent that we may be tempted to set their houses on fire or kill them out rightly. This kind of thing can make you go in search of information on how to ruin someone's life. If the target lives in your neighborhood, you can find a combination of stalking, trolling, and sometimes some IRL bullshit from the following link:
Additionally, you can get inspiration from the experience of others as outlined below.
How to Ruin Someone's Life: Get Inspiration from Others' Experiences
If someone hates you with passion, one easy way to ruin their lives is to live a very happy life and forgive them all their wrongs in the open. This is the only solution I can remember right now.
From corn-fed pig
Another very effective tip on how to ruin someone's life is by leveling a false accusation against them about practicing pedophilic lifestyles. Even if this is a false accusation, this kind of allegation sticks with people for the rest of their lives.
This is one reason I will never work with children in my life. Don't ask me for the whole story, I won't tell.
Store some child porn in your target's life. FBI will arrive their house in less an hour and the person will be labeled a pedophile for life and won't be able to secure a job, get a date, or any kind of emotional happiness. People get tempted to harass their targets beyond this point, but we do not advice this because it may drive them to suicide; only the living can feel pains. So wait for a couple of years and add some doses of laxatives to their water supply once every month.
Store some materials used for bomb production in their home and mount an ISIS flag near their house. Write something that says they plan to bomb a major public place and how they can't wait to be with god in paradise or anything like that. For more effects, store some child porn in their home, clog up their toilet to the rim with animal waste to make life more unbearable for them.
Then inform the police about the person's residence and evidences, and place an anonymous call to the target warning him to flee his home because someone is framing him of impending terror attack. This will put the target on the run, which will further aggravate the situation.
To make sure he doesn't run and ends up getting hurt in a hot police pursuit, drain his car of fuel and replace the fuel with some dog urine, while you relax with a bottle of martini.
Get them to sign up for as many things as possible. Call them ceaselessly with unending sales promotion and information. This will make them victims of constant harassment and they won't be able to tell why.
You can also pay a provocative dancer whose style is against their sexual orientation and preferences and get the dancer to go perform for them in the office.
If the target is married, you can send him/her a love card that says, I'm sorry, I want you back in my life. Ask if they have forgotten the passionate nights you two spent together when the going was still good and have the card delivered when you know their partner will be home to get it.
Get the target's phone number.
Carry a sharpie wherever you go and have their phone numbers inscribed in all public bathrooms.
After writing the phone number, add something that says the number is offering a variety of sexual services.
First, try to seduce the person, so you two can start dating. After dating him/her for some years, get married to him/her. Make sure you have no kids together. Build an environment characterized by love and mutual support, with very rich family tradition.
Now we come to a very important point on how to ruin someone's life. To destroy their life, make sure you die while they are still alive. This way, they will stay alone and feel lonely for the rest of their lives.
If they are engaged in any shady business, make sure you report them to either the DEA or the IRS. Let their baby-mama or ex-wife know where they keep their money hidden. If they are having an affair with your spouse, call their parents. Make sure they do not get into their preferred professional school, using your connections. You can even take some illegal steps like setting up a new fake email address, sending a mail to yourself using the fake email address and claiming that the email came from your target. Take the mail to the police and file an affidavit against the target with claims that they are trying to destroy you. This was exactly what someone did to me in attempting to ruin my life.