You have to check for following things.
1) Remove custom field entry in table "fields_meta_data"
2) Remove field from module_name_cstm table
2) Remove file from custom/extension/modules/<Yourmodule>/Ext/Vardefs/sugarfield_<Field name>.php
3) Remove field from all the view if you have added any.
Do quick repair & rebuild.
Reference: https://community.sugarcrm.com/thread/26711