@InvincibleAbhay no you can't open a closed team. They already give you a warning while closing: 'Closing a team is definite, once you close, you won't be able to reopen it. Are you sure you want to close?' And then they give choices: Yes/No.
So, remember this the next time you try to close a team.
One day a user called InvincibleAbhay went wondering in the team settings... Then he saw a mysterious "Close team" button. His parents had told him not to press the button but InvincibleAbhay had to press it, no one knows why lol. Then he realised oh no I can't reopen my team! Came to the forums to find help. He asked everyone how to reopen his team but he always got the same answer: You can't reopen a closed team. InvincibleAbhay learnt from his mistake and will think TWICE before closing a team!