The validate script would need to call a preventDefault() to stop the browser from taking it’s normal course of action.
That a side, you don’t really need this validate script, you can use ‘required’ in your HTML
<form class='events-form' name='events' action='#' method='post'>
<label for="datemin">Date of Event:</label>
<input type="date" id="datemin" name="datemin" min="2020-02-01" required>
<label for="ename">Event name:</label>
<input type="text" id="ename" name="ename" required>
<label for="Time">Time of Event:</label>
<input type="text" id="Time" name="Time" value=" " required>
<fieldset>
<legend>Selecting Location</legend>
<label>Select Location</label>
<select id = "Location" required>
<option value="">Please choose a location</option>
<option value = "L1">Perth</option>
<option value = "L2">Duidgee Park, Toodyay</option>
<option value = "L3">Canning Highway</option>
</select>
</fieldset>
<fieldset>
<legend>Selecting Price</legend>
<label>Select Price</label>
<select id = "Price" required>
<option value="">Please choose a Price</option>
<option value = "P1">$20</option>
<option value = "P2">$30</option>
<option value = "P3">$40</option>
<option value = "P4">$50</option>
<option value = "P5">$80</option>
</select>
</fieldset>
<label for="quantity">Quantity:</label>
<input type="number" id="quantity" name="quantity" min="1" max="99" required>
<input type="submit" value="Submit">
</form>