app3.py

import gradio as gr

def collapse_sidebar():
    # return a config change for the Sidebar component
    return gr.update(open=False)

with gr.Blocks() as demo:
    with gr.Sidebar() as sidebar:
        gr.Markdown("Sidebar content")
        close_btn = gr.Button("Close sidebar")

    # clicking the button tells Gradio to update the Sidebar's 'open' prop
    close_btn.click(fn=collapse_sidebar, inputs=None, outputs=sidebar)

demo.launch()