You may add a hidden value inside the form to add the id:
<td>
<form action="CarServlet" method="get">
<input type="hidden" name="carId" value="<%= resultList.get(i).getId() %>" />
<input type="submit" value="Remove" name="remove">
</form>
</td>
Since you're already using request attribute, it would be better to stop using scriptlets at all and use Expression Language + JSTL.
<table>
<thead>
<!-- current thead -->
</thead>
<tbody>
<c:forEach items="${ResultList}" var="car">
<tr>
<td>${car.carMake}</td>
<td>${car.model}</td>
<td>${car.carYear}</td>
<td>${car.carColour}</td>
<td>${car.information}</td>
<td>
<form action="CarServlet" method="get">
<input type="hidden" name="carId" value="${car.id}" />
<input type="submit" value="Remove" name="remove">
</form>
</td>
</tr>
</c:forEach>
</tbody>
See how code above is better for readability and maintainability compared to your original code that uses scriptlets.