You can have a button that changes the brick from a normal color to a trans color.
These events on the button:
0 [ticked] onActivate>NAMED BRICK[brick]>setColor>Your color here.
1 [unticked] onActivate>NAMED BRICK[brick]>setColor>Your trans color here (look towards the end of these colors and you will notice that there is colors in the order they are in the trans paints, these are transparent)
2 [ticked] onActivate>self>toggleEventEnabled>0 1
use [brick] as the name of the brick you want to change from a normal to transparent color.