TRIM — Trim

Trims objects at their intersections.

Trims the part of an object that lies between its intersections with other objects (the cutting edges) or between an intersection and its end.

Usage

Enter TRIM (or TR) or click Trim on the ribbon.
In Quick mode (the AutoCAD 2027 default: variable TRIMEXTENDMODE=1) you do not select the edges: every object in the drawing is a cutting edge. Click the part to remove from each object: the clicked piece is removed up to the nearest intersections. The prompt repeats to trim more.

Select object to trim or shift-select to extend or [cuTting edges/Crossing/mOde/Project/eRase]:

Select cutting edges... Select objects or [mOde] <select all>:

cuTting edges: select the cutting edges instead of using every object.
Fence (Standard mode) and Crossing: draw a fence; each object it crosses is trimmed where it crosses.
mOde: switch between Quick and Standard.
Project: None, Ucs or View (PROJMODE; stored: it does not change the result in 2D).
Edge (Standard mode): Extend prolongs the edges (EDGEMODE) to trim against their extension.
eRase: erases the objects you select.
Undo: undoes the last trim.

Lines, arcs, circles and polylines can be trimmed and serve as edges. Trimming a circle leaves an arc; trimming the inside of a line or polyline splits it into two objects.
Hatches are trimmed too: the clicked piece is removed between the edges and the rest stays a single, non-associative hatch.
Objects to trim are picked one at a time with a click on the part to remove. The previous selection is not used.
With Shift held while clicking, it extends instead of trimming. To extend with the same edges use EXTEND.
Ellipses (whole or arcs) and open splines are trimmed like other objects and also act as cutting edges. A closed spline is not trimmed.