The taper attachment would be difficult to remove. Monarch probably used a telescopic taper attachment, which is to say one that could be used without detaching the cross feed nut. This requires a two piece cross feed screw, the threaded portion can slide in and out of the portion that attaches to the cross feed dial/handle. However, the threaded portion of the cross feed screw is captured at the other end by the taper attachment. Without the taper attachment on the other end, the threaded portion will just come out when you try to move the cross slide.
In short, removing the taper attachment will either require a new cross feed screw, or a hack job on the existing one that would render the taper attachment unable to be reattached.
If you ever have to sell or pass along the lathe, a working taper attachment is a big draw. Also, the relevant natural laws also suggest that after you disable the taper attachment, you will receive a job that necessitates one...