What is a clear indicator you should stop being friends with someone?

When you have to overlook things they say and do. When you’re too embarrassed of them to introduce them to other friends or family. When it feels like they only take from you and never give anything back.
At this point if I don’t trust a friend with my house key, I don’t want to be friends with them.
Also, I’m too tired to have feel-good friends. If I don’t trust them to keep me safe if I’m black out drunk, or having a mental breakdown, it’s not worth it.

When the friendship becomes so lopsided that you’re putting in all the effort and it seems clear they could take or leave you. I’ve had to drop friends when it got to that point. :(

When you see that the friendship turned toxic. Lost an old friend because he took sides with a dictator and insulted, me because I didn‘t share his believes.
He couldn‘t see the point that I was upset, that he hurt my feelings instead of sticking to the facts and blamed it on me.

I have many acquaintances, few real friends. When they are judgmental of others or talk behind their backs, you can bet they will do the same to you.

They chronically can't find any time for you.
You both became different enough to feel strangers around each other.
You find out they actively work against your own interests and support ideas and institutions that intend to take away your rights or abuse you.

when they take but don't give in return.
when they break your trust
when they overstep your boundaries.

When it’s you doing all the giving and nothing in return…

If you find that their presence is more stressful than their absence.

Lying

Violence.

When they hurt more than they heal.

They block you?

They commit felonies

If we go somewhere and they steal something

When you actively avoid them

When they are bad or a bad influence.. 😏

When the courts tell me so

When you see them dropping a clear liquid into your drink while they encourage you to turn your head away by saying... "Look... what is that?"

They're extremely needy and clingy, almost love bombing-ish.

They like Hootie and the Blowfish. A lot. 😜

They only want to see you when they want something

They smell.

The fact that the question comes up is an indication.

They knock up your wife but won't give you a reach-around.