Why does Napoleon do away with the meetings? What does Squealer say about all of it?

Napoleon abolishes the meetings because he is asserting his complete control. Over time, we come to see that Napoleon is nothing more than a tyrant. He, none the less, continued to present himself as if he weren't. On the day he abolishes the Meetings.... he publicly proclaims his total authority.

Squealer continues by smoothing things over with propaganda.

Afterwards Squealer made a round of the farm and set the animals’ minds at rest. He assured them that the resolution against engaging in trade and using money had never been passed, or even suggested. It was pure imagination, probably traceable in the beginning to lies circulated by Snowball. A few animals still felt faintly doubtful, but Squealer asked them shrewdly, “Are you certain that this is not something that you have dreamed, comrades? Have you any record of such a resolution? Is it written down anywhere?” And since it was certainly true that nothing of the kind existed in writing, the animals were satisfied that they had been mistaken.