There’s no setting to configure the toolbar, but it’s possible through themes and plugins.
It would be nice to have this feature, so I’m going to re-categorize it as a feature request.
For now, buttons can be hidden with CSS… for example:
.d-editor-button-bar {
.local-dates { // hides the date button
display: none;
}
}
or to hide an option from the 
menu
.toolbar-popup-menu-options {
[data-name="Build Poll"] {
display: none;
}
}
With CSS it’s also fairly straightforward to reorder items in these menus… you can do something like:
.d-editor-button-bar {
.local-dates { // moves the date button to the beginning
order: -1/
}
}
We have a guide for figuring out how to change CSS over here:
All that said, the more difficult change is moving something to/from the dropdown menu and into the main toolbar (or vice versa). You’d need to hide the original button with CSS and then add a duplicate button using the API.
Looking at an example theme component, like Discourse Gifs gives a general idea of how that’s done… though this gets tricky if you’re not a developer.