Why was King Charles excituted?

Answer 1

You mean "Why was King Charles I executed"

Charles was accused of treason against England by using his power to pursue his personal interest rather than the good of England. The charge against Charles I stated that the king, "for accomplishment of such his designs, and for the protecting of himself and his adherents in his and their wicked practices, to the same ends hath traitorously and maliciously levied war against the present Parliament, and the people therein represented...", that the "wicked designs, wars, and evil practices of him, the said Charles Stuart, have been, and are carried on for the advancement and upholding of a personal interest of will, power, and pretended prerogative to himself and his family, against the public interest, common right, liberty, justice, and peace of the people of this nation