The idiomatic use of decline does not seem apparent when looking at the dictionary definition, for example, Dictionary.com. It says,
Def. 2. to express inability or reluctance to accept; refuse with courtesy: to decline an invitation; to decline an offer.
What is being refused is something that will be answered with a "yes" or "no": an invitation to a party, a proposal of marriage, a charge to a credit card. These may all be declined.
Whether the report may be declined depends on what type of report it is. If it is a report of electric meter usage, it probably could not be declined. It has neither "yes" nor "no" as a response. If it is a report of a patient's condition, it would similarly be unidiomatic to decline the report.
However, if the report were from a Senate committee that the full Senate did not want to receive or air, then the report might declined. That is because the report may carries a motion that would require debate or action on the part of the full Senate.
Here is a page that deals with Robert's Rules of Order, which the Senate uses in a modified form. One portion says,
The society cannot alter the report of the board. It may decline to indorse it, or even to allow it to be printed, but it cannot make it appear that the board stated anything different from what it has reported.
So some reports may be declined. It depends on the report.