A family of Microsoft relational database management systems designed for ease of use.
It's an old activex control no longer needed in most cases, because we now have a small calendar icon built in for date fields.
Code window > Tools > References and uncheck it if it is listed.
Then Debug > Compile
If no errors, you're probably fine.
Or you may have to open each form in design view to see if it has a calendar control on it, then remove that and fix up possible code that was using it.