How do you unlock score times 10 on Lego star wars the original trilogy PSP?

You can't unlock Score Times 10 in LEGO Star Wars: The Original Trilogy for the PSP. This feature was not included in the PSP version of the game.

It's possible you're thinking of the GameCube, Xbox, or PS2 versions, which did include Score Times 10 as a bonus unlockable feature. This option allows your score to be multiplied by 10, making it much easier to reach higher scores and unlock more bonus content.

Unfortunately, the PSP version of the game doesn't have this feature.