Fastening methods are classed as permanent or temporary, and a bolted joint belongs firmly to the temporary group.

In a bolted joint a bolt passes through the parts and a nut clamps them, holding everything by the axial tension in the bolt rather than by fusing or deforming the metal.

Because the nut simply screws on and off, the joint can be tightened during assembly and later unscrewed without cutting, grinding or otherwise damaging the components.

This quick make-and-break ability is the main reason bolted joints are preferred, since parts can be assembled, inspected, replaced and reassembled easily during maintenance.

Saying they are difficult to remove or permanent contradicts this very advantage, as those descriptions fit welded or riveted joints instead.

Being heavy in weight is not an advantage at all and is not a defining feature of a bolted connection.

Hence, the answer is Easy to assemble.