In The Small House at Allington, Anthony Trollope describes a failed dinner party:
Nothing was said on that evening which has any bearing on our story. Nothing, indeed, was said which had any bearing on anything. The earl's professed object had been to bring the squire and young Eames together; but people are never brought together on such melancholy occasions. . . . When the Guestwick fly came for Mrs. Eames, and the parson's pony phaeton came for him and Mrs. Boyce, a great relief was felt, but the misery of those who were left had gone too far to allow of any reaction on that evening. The squire yawned, and the earl yawned, and then there was an end of it for that night.
The earl had planned this dinner party for the sole reason of effecting a meeting between two of his friends. However, the plan became doomed when certain necessary people declined to attend and other unnecessary people were invited in their place. The dinner party went forward; conversation fell flat; so did the interactions of the two friends. Everyone regretted the evening.
The same situation happens to writers and storytellers when a scene or other portion of a story becomes useless. Whether the scene arose as a natural part of the story, or had to be constructed to achieve a particular development (as when the Trollope's earl planned an artificial meeting for his friends), we later discover that the scene is falling flat. Perhaps it makes the earl and the squire yawn. It's boring, it doesn't fit with the rest of the story, or it's not achieving its purpose.
It's always painful to take a hard look at something we've written to decide whether we should axe it—especially if we have a particular loyalty to the scene (or character, setting, or turn of phrase) or we've worked hard on it. And we may find that we don't need to axe it after all. However, we must go through the process of considering its destruction, since a good story has no room for anything extraneous. If a part of a story isn't doing its job, it must go. Cutting a section is painful in the moment, but strengthens the story in the long run.
When evaluating a problematic area of a story for possible deletion, carefully consider the following questions.
Is it necessary to the plot? Does it move the plot forward, build necessary tension, resolve a plot conflict, or provide important information?
Is it necessary for character development? Does it illustrate who a character is in important detail, show why or how a character changes, or explain a character's motivations?
Is it necessary to the story's setting? Does it help readers to visualize the story's physical setting in an important way? Does it explain the story's milieu so that readers can understand the context of the plot and characters?
If the answer to any of the above three questions is yes, is or can the same object be achieved in another scene? That is, if you delete this scene will the story still stand? Should you work the objective into another part of the story, or replace this scene with a new one?
Based on your answers to these four questions, you will either be able to cut the scene with a clear conscience, or revise it with a clearer sense of how to improve it. Don't let this be an instance where "nothing was said . . . which had any bearing on our story."
Interestingly, in the last chapter of The Small House at Allington, Trollope includes a completely extraneous subplot about the squire and his gardener. It goes on for several pages and has no reason for existence whatsoever. Even the greatest of writers can't let go sometimes!