Hi @LeoImLeo ,

What do you mean by "weight center of the desk"?

If it is Geometric-Center, then you can use MOVE command to move the "desk" object using this command sequence:

Command: MOVE
Select objects: 1 found <- Select desk
Select objects: <- Hit Return
Specify base point or [Displacement] <Displacement>: _gcen of <- Use Geometric Center object snap
Specify second point or <use first point as displacement>: #0,0 <- Type this and hit Return

HTH