Remove empty space from the end of a line in a richtextbox

Remove empty space from the end of a line in a richtextbox

How can I remove empty space from end of line in a richtextbox
Original string
ALTER TABLE "TBLCONCESSIONAIREOFFICES" ADD ("CNCO_IRISAUTOCONFIRMINVOICE"
NUMBER(2,0) DEFAULT 0 --0: No, 1: Yes;
);
Expected result:
ALTER TABLE "TBLCONCESSIONAIREOFFICES" ADD
("CNCO_IRISAUTOCONFIRMINVOICE" NUMBER(2,0) DEFAULT 0 --0: No, 1:
Yes);
My code:
string[] lines2 = comparedResultRTB1.Lines;
lines2.ToString().Replace("; );",");");