Can my startup co-founder legally remove me from the company?

I co-founded a tech startup in Bangalore with a friend, and we both own 50% of the shares. Recently, we had a disagreement on business strategy, and now he is trying to oust me from the company. He has changed passwords to our online accounts and is holding meetings without me. We didn't sign any formal agreement about handling such situations. I am worried about losing everything we built together. What legal steps can I take to protect my position and ensure fair treatment?