The company was forced to 'declare bankruptcy'. [=to formally say in a legal document that it was bankrupt]
He 'declared' himself the winner. = He 'declared' that he was the winner. = He 'declared victory'.
His 'declared' [=publicly stated] aim/goal/intention is to improve the city's downtown area.
(..) ... is dead! From this day forth... ... you'll put your faith in me. Harry Potter is dead! And now it's the time to declare yourself. Come forward and join us... ... or die! Draco! Draco. Draco. (..)2011 Harry Potter and the Deathly Hallows: Part 2