I submitted a conference paper that was too long...what now?
Keeping in time is mandatory

In general, you can expect to be cut off if you are over the time limit, so you definitely should shorten your presentation - it's very likely that important parts of your talk are at the end so it's very important not to lose the ending!

In most fields, presentations are very, very different from the actual content of the paper - if someone wants to read the paper, they can do so at any time; but the presentation should cover why they'd want to read your paper afterwards and also explain things that might be easier to show or demonstrate rather than read about.

Even if in your field tradition is to read the paper as-is, that is optional but keeping the schedule is mandatory. I would suggest to reduce some parts that describe the background/foundation/earlier results which would be known by the conference attendees but might be less known for a general reader of your paper. You should mention earlier work, but you don't need to go into detail about that even if you do so in your paper. 

Keep the focus of your talk on the novel parts of your paper, and also make sure cover in detail the motivation of this research and it's wider context in your field.