Can I use B1/B2 visa from previous employer to visit USA for pleasure?

I got my B1/B2 10 year multiple entry visa ago when my previous employer wanted me to go to US for a project meeting.
They also arranged an an invitation letter from their US sister company too.

I have left that company and now work for another one.

Can I use this visa, which is still valid to visit US for my own vacation?

Yes, you can.
The B1/B2 visa is not tied to any specific employer in general.

If the visa is still valid, you can use it to enter US.