I have created SamplePage.php and Build db /dev/build. I will be have new table. If I delete SamplePage.php and rebuild DB the table it not delete.

How to auto delete or clean database table after delete SamplePage.php or something page?

Ext:
Step 1 : I have created 5 page controller and 5 data object files.
Test1.php
Test2.php
Test3.php
Test4.php
Test5.php

Step 2: I have build DB /dev/build?flush=all

Step 3: I have deleted 5 files in folder mysite/code/ and Build DB again.
delete Test1.php
delete Test2.php
delete Test3.php
delete Test4.php
delete Test5.php

Step 3: I check in Database but table in database is not delete.

Thanks.

I've found it keeps old fields as well, I just remove them manually in MySQL

This is more of an architectural thing. The idea being if you change your mind of need to roll back to old code it will still work and the data will be intact.

You might want to search/ask in the Data Model forum on how to discretely prune your tables. Personally, I just run alter statements after I'm sure they can be deleted.