Hi there!
Thanks for your query.
There is no default way to do that. However, yu can try some custom CSS proposed below.
If you want to hide the the "Class Size" field from the backend https://prnt.sc/1vh4b3j then you can use the following code in your custom CSS:
label#jform_class_size-lbl, #jform_class_size {
display: none;
}
If you want to disable the "Class Size" field from the frontend https://prnt.sc/1vh4dbx
then you can use the following code:
.course-info li.size {
display: none!important;
}
Here is the code to disable the Subject List from frontend:
.subject-list-wrapper {
display: none;
}
If you want to remove the subject list from the backend, then you can click on each of the subjects shown in the screenshot:
https://prnt.sc/1vh3g1p
Note: Path towards custom CSS: Extensions>Templates>Styles> Click on your current default template name then choose Template Options. Then find custom CSS within the custom code.
Best Regards