Actually, I don't like my boss because (his sense is still oldattitude is outdated / he is too old school). Actually, I don't like my boss because (his attitude is outdated / he is too old school).

I gave two options here, the latter being more casual.

He believes that allthe people who work in the office should go out to drink alcohol together so that theyfter work so they will get along well. He believes that the people who work in the office should go out to drink after work so they will get along.

"Go out to drink" already implies alcohol, no need to state it unless you want to insist on it.

However, I can't drink at allcohol. However, I can't drink alcohol.

Here, it would be good to say "alcohol" for emphasis

I'm often saitold by him to go to drink, and it's very bothersome. I'm often told by him to drink, and it's very bothersome.