Crop all open in Illustrator files

Glad it worked! Here's a version that applies to every open document.

var docs = app.documents;
for (var i = 0; i < docs.length; i++) {
    removeAllButMap(docs[i], false);
}
alert('Processed ' + docs.length + ' files.')

function removeAllButMap(doc, showInfo) {

    app.activeDocument = doc;

    // select all and remove one level of clipping masks
    executeMenuCommand('selectall');
    executeMenuCommand('releaseMask');
    doc.selection = null;

    // loop over the path items, removing each
    // one that doesn't match the criteria
    var items = doc.activeLayer.pageItems,
        keepCount = 0,
        removeCount = 0;
    for (var i = items.length - 1; i >= 0; i--) {
        var item = items[i];
        if (
            item.typename == 'GroupItem'
            && item.clipped
            && item.pageItems.length > 1
            && item.pageItems[0].clipping == true
            // this is the width and height of the map masks:
            && isNearEnough(item.pageItems[0].width, 1299.21, 2)
            && isNearEnough(item.pageItems[0].height, 1639.09, 2)
        ) {
            keepCount++;
        } else {
            item.remove();
            removeCount++;
        }
    }
    app.redraw();
    if (showInfo)
        alert('Removed ' + removeCount + ' items, and kept ' + keepCount + ' items.');
}

// function that compares a value within tolerance:
function isNearEnough(n, m, tolerance) {
    return Math.abs(n - m) < tolerance;
}