Notice of dropping defendants refers to a notice that is filed to inform that one of the original defendant to the lawsuit is dropped from the suit. Dropping a party means dismissing one of the original defendants to the lawsuit. In other words, if the plaintiff feels that one of the defendant is no longer necessary for their case, that defendant can be dropped.
Example of a State Statute ( Florida) on dropping parties.
Fla. R. Civ. P. 1.250 (b) says parties may be dropped by an adverse party in the manner provided for voluntary dismissal in rule 1.420(a)(1) subject to the exception stated in that rule. If notice of lis pendens has been filed in the action against a party so dropped, the notice of dismissal shall be recorded and cancels the notice of lis pendens without the necessity of a court order. Parties may be dropped by order of court on its own initiative or the motion of any party at any stage of the action on such terms as are just.