If you delete the database field with pgAdmin3 or directly from a console it should disappears with all his entries. Last time I've tried it worked fine if it is just in one table, don't do it if is a field related to another table.  Then you need to delete the field you dropped from the python file too.

In that way even if you rebuild your module the field will not shows again. It's a dirty hack, do a backup before doing it and pay attention with view definitions: if the field you deleted is till declared in a view Odoo will rise an error and could stop the server.

Hi,

Here's my version of Benjamin's solution for ODOO 10 :

xml :

< odoo>

< data>

 < function model="clean.field" name="init_remove_field_api7" eval="['account.indicateur.custom.ltq','total_achats']" / >

< /data>

< /odoo>

py file :

import logging
from odoo import models, fields, api, _, SUPERUSER_ID, tools
from odoo.models import TransientModel

_logger = logging.getLogger(__name__)

class CleanField(TransientModel):

    """ Classe pour supprimer un champ de la BDD."""
    _name = "clean.field"

    @api.model
    def init_remove_field_api7(self, model_name="", field_name=""):
        """Entry function remove Field (called with API7)."""
        if model_name and field_name and type(model_name) == str and type(field_name) == str:
            table_name = model_name.replace(".", "_")
            _logger.info(u"init_remove_field_api7 : removing database field {}.{}".format(table_name, field_name))
            return self._remove_field(model_name, field_name)
        else:
            return False

    @api.model
    def _remove_field(self, model_name="", field_name="", context=None):
        """Removes the Field from the database."""
        query1 = """SELECT 1 FROM ir_model_fields WHERE model = '{}' AND name='{}';""".format(model_name or "", field_name or "")
        self.env.cr.execute(query1)
        fields = self.env.cr.fetchall()
        if fields:
            table_name = model_name.replace(".","_")
            query2 = """DELETE FROM ir_model_fields WHERE model = '{}' AND name = '{}';
                        ALTER TABLE {} DROP COLUMN {};""".format(model_name, field_name, table_name, field_name)
            _logger.info(u"_remove_field : query = {}".format(query2 or "None"))
            self.env.cr.execute(query2)
            self.env.cr.commit()
        return True

https://www.odoo.com/forum/help-1/question/delete-record-from-database-with-unlink-new-api-solved-73404