This can both be done in the page editor.
This is all explained in the rapid developer course:
https://academy.mendix.com/link/paths/31/Become-a-Rapid-Developer
Hi Wenyu,
The large arrow may be coming from a widget on your Home_Web page or from the navigation layout applied to that page. I would check the following steps to identify and remove it.
1. Check the Home_Web page
Open Home_Web in Studio Pro.
Inspect the page structure and look for an Image, Icon, Button, or other widget displaying the arrow.
If the arrow belongs to a widget that you do not need, remove that widget and run the application again.
2. Check the page layout
If the arrow is not present in the page itself:
Open the properties of Home_Web.
Check which layout is assigned to the page.
Open that layout and inspect its header, sidebar, and navigation-toggle widgets.
If the arrow is part of the navigation layout, adjust the relevant widget or create a custom layout based on the existing Atlas layout rather than modifying the original Atlas layout directly.
Mendix layouts define the common structure shared by pages, so an element in a layout can appear on multiple pages.
3. Display your data
Once you identify the arrow's source, check that Home_Web contains the appropriate Data View, List View, or other data widget, with a valid datasource and the required entity access permissions.
If the arrow disappears but the data still does not appear, troubleshoot the datasource separately.
Reference: Mendix – Using Navigation Layouts
Could you share a screenshot of the actual application showing the large arrow? That would help identify whether it comes from a page widget, an icon, or the navigation layout.
Hope this helps! If you find this answer helpful, please mark it as the accepted answer.