Don't be fooled by the blue highlighting on data in a field in the Report Designer. Just because the data is highlighted, this does not mean you can do something to it (like delete or change it).
If you do not see a drop down arrow, or the X tool in dark blue, you cannot do anything to the highlighted field. Generally, to remove or change something, you have to go to the lowest level and work backward. If you picked an application, then an object, then a record, and from the record a set of fields, to change the application you need to delete the fields, then the records(s), then the object(s), before you can delete or change the application. The only hint about the restriction is that the X is greyed out at the application, object, and record level, and only enabled at the field level. Fortunately, you can delete fields from the field list without also needing to remove them from the layout.
It would be extremely helpful if MEDITECH provided help if the user hovers over or tries to click a greyed out tool. The alternative is that the user has to imagine the reason that an operation has been disabled and experiment to see if the theory is accurate.
After you have selected your application, object(s), and record(s) on the Main page, you define the general characteristics of the report on the General page. Most of the page is straightforward. It is unfortunate that they have included a whole attribute section that does nothing (so far), with no hint that it is just hanging around waiting for some future features. Also, the "Show Report Selections in Section" prompt apparently only does something when a report is scheduled; it does not automatically put the run time selection values in the report header when a report is printed directly.
Sorts and selects have been split into two pages:
On the fields page, the record/segment list is shown at the top and fields that you have selected from that record/segment are shown when the record is highlighted: