You can drag the sidechains with the mouse.
Get rid of the clash by clicking and dragging one of the sidechains away from the other.
Technical stuff: this puzzle has only three segments. The orange hydrophobic sidechain on the left is tyrosine. The blue hydrophilic sidechain on right is either glutamate or glutamine, which have the same shape. There's a segment in between the two sidechains, which is glycine. Glycine has no sidechain.