In order to help Admin could limit the number of events which are created by any user of groups, please follow the instruction of this article.
From your AdminCP area>Apps>Installed>Events>User Group Settings>Select the Group which will be applied the setting. For assuming that you want to limit the number of events can be created by Registered User, then let's choose the Groups is Registered User.
Then find the setting Maximum number of event can create? and enter the number of events could will be created.
Note: For unlimited add "0" without quotes.
Last but not least, please don't forget to press Save Changes to apply the setting.