Removing legend items without specifying the layer group with PyQGIS

Question

How can I remove multiple layers from legend in the MapComposer without removing them from the canvas and without having to specified their group ?

In the code below I have to add group = root_group.findGroup("group_name_1") to remove the layers belonging to this group but I would like to find a way to remove the layers without having to indicate their group name... Is it possible ?

layers_to_remove = []

legend = [i for i in layout.items() if isinstance(i, QgsLayoutItemLegend)][0]
root_group = legend.model().rootGroup()  
group = root_group.findGroup("group_name_1")  
legend.setAutoUpdateModel(False)
for layer in layers_to_remove:
    root_group.removeLayer(layer)  

Answer 1

You can find the group dynamically by getting the name of the layer's parent in the layer tree:

# reference to the project
p = QgsProject.instance()

# names of layers to remove from legend
layers_to_remove = ['layer1', 'layer2']

# the layer tree
root = p.layerTreeRoot()

# layout manager
manager = p.layoutManager()

# first layout (can also use manager.layoutByName() )
layout = manager.layouts()[0]

# get legend
legend = [i for i in layout.items() if isinstance(i, QgsLayoutItemLegend)][0]

# disable auto-update
legend.setAutoUpdateModel(False)

# legend model
model = legend.model()

# the root legend group
root_group = model.rootGroup()

# loop through layer names
for layer_name in layers_to_remove:
    # find layer in project
    layer = p.mapLayersByName(layer_name)[0]
    
    # get layer tree layer instance of layer
    layertreelayer = root.findLayer(layer.id())
    
    # get the parent of the layer tree layer (layer tree root, or group)
    parent = layertreelayer.parent()
    
    # if the parent is a group and has a name, find it and remove the layer
    if isinstance(parent, QgsLayerTreeGroup) and parent.name():
        group = root_group.findGroup(parent.name())
        group.removeLayer(layer)
    # remove layers that are not in a group
    else:
        root_group.removeLayer(layer)
        
# update legend
legend.adjustBoxSize()
layout.refresh()

Note: there will need to be some extra logic (e.g. recursion) added to deal with sub-groups.