I was able to figure out how to remove the Progress and Details sidebar from a specific Learning Plan landing page, as the stakeholder thought it was “too busy” and wanted it removed. Here is an example of what the sidebar looks like (right side of image).

Here is what it looks like removed.

Here is the CSS code to remove it (the identifier for this LP is 87 found in the URL - Uyour domain name].docebosaas.com/learn/learning-plans/87).
/** Hides Progress, Keep Learning From, and Learning Plan details on Street Playbook LP page **/
.lrn-learning-plan-overview-87 .ui-col-24.ui-col-md-8.lrn-content-overview-sidebar {
display: none;
}