Learn French: Le chef est en train de démolir le mur en briques. - The boss is in the middle of demolishing the brick wall.

Yes, you could say Le chef démolit. French does not have a direct equivalent to the English present continuous (is demolishing). Usually, the simple present covers both demolishes and is demolishing. However, when you want to emphasize that an action is in progress right this second, you use être en train de followed by the infinitive (démolir).

Why is chef translated as boss instead of chef (cook)?

In French, un chef broadly means a chief, leader, or head of a team. A professional cook is a chef cuisinier, though it is shortened to chef in the kitchen. If you are talking about a company boss or owner, you would generally use le patron.

Why is it en briques? Can I just put the words together like le brique mur?

No, French does not allow you to use a noun directly as an adjective before another noun like we do in English. To describe what something is made of, you place the material after the noun using the preposition en (or sometimes de). Therefore, the brick wall becomes le mur en briques.

Why is démolir in the infinitive form rather than conjugated to match le chef?