In the C++ world every QWidget provides access to its children.
https://doc.qt.io/qt-5/qobject.html#children
You can shotgun blast via
QObjectList *widgetList = findChildren();
step through in debugger to see what each child is
You are looking for a buttonGroup or buttonBox. Once you have a pointer to it you can simply ->hide()
You can remove some of the mystery if you create a QPoint() object known to be within the "panel at the bottom" but not in a button.
https://doc.qt.io/qt-5.14/qwidget.html#childAt-1
Qt is OpenSource. You can pull down the code
https://download.qt.io/archive/qt/
Find the source file that constructs the page you want, and look at its constructor. That will tell you what button box/group is and if it got a name.
Most likely there is something simple like buttons.hide or buttons.visible = false
I don't use QML or JavaScript
I ass-u-me your "buttons" are coming from a ButtonGroup
https://doc.qt.io/qt-5/qml-qtquick-controls2-buttongroup.html
So you just need to find the ID assigned your ButtonGroup on that page and
buttonGroupId.visible = false
If you want real help you have to post a link to complete code that compiles and runs. You also need to indicate what platform you are on.
Edit after doing some more digging:
You still need to post full code via some zip file or something, but here is the documentation trail.
https://doc.qt.io/qt-5/qml-qtquick-controls2-buttongroup.html#buttons-prop
https://doc.qt.io/qt-5/qml-qtquick-controls2-abstractbutton.html
https://doc.qt.io/qt-5/qml-qtquick-controls2-abstractbutton-members.html
When you track it all the way back to AbstractButton you come to what should be good enough for you.
parent : Item
https://doc.qt.io/qt-5/qml-qtquick-item.html#parent-prop
If buttons.NextButton.parent != null then you can buttons.NextButton.parent.visible = false