Editing for Cohesive Plot
Now that you have written your story, try summarising it again (this will probably look a little bit different to your plan). Make sure you include the most important information from each scene - e.g. instead of "Sam and Ryan talk about burglar, disagree on who it might be", you would write "Sam tells Ryan he suspects his mother is the burglar because her work shifts are always at night, Ryan disagrees and suggests it might be their neighbour who is suddenly spending more money".
Starting at the END of your story and working backwards, look at each major event and answer the question "why did this happen?" If the answer is not obvious from another scene in your story, make a note of it here. Can you answer the question by adding more information to an existing scene? Do you need to write a new one? Is this scene necessary?
Imagine your story as a flowchart, where one event leads to another. If you have a subplot, you might have two flowcharts that connect to each other in a pivotal scene. Are there any events that do not fit in your imaginary flowchart, scenes that don't connect to other events in the story? These may be "filler" scenes to draw out time, "infodump" scenes that are there to give the reader information rather than move the story forward, or scenes that are meant to demonstrate a character's personality or state of mind.
Now comes the hard part. Delete the scenes that are irrelevant to other events of the story. Don't worry, you've saved a copy of your draft and you can re-add them later, if at the end you still think the story would be better with them. But sometimes the hardest part of editing is cutting out perfectly good words, maybe even beautiful sentences. Be ruthless!
Next, go through each scene and cut any paragraphs that don't contribute something important. Ask yourself "would a reader be able to understand what was going on without this paragraph?" Do not be concerned about your word count, that will move up and down plenty of times before we're finished, and a story should only be as long as it needs to be.
Look again at your story and summary. Do all scenes work towards a common goal? Does it include all the information needed to make sense? If not, go back through this process a second time.
Have someone else read your story and ask them if they understood it. Ask them to summarise what happened. When you are satisfied that your plot is logical and succinct, move on.