I've got a problem with access rules. When I started creating my custom module and didn't know a lot about odoo I created a model named hr.pay_history. After that I totally changed the model and changed the _name to hr.pay.history. 

Now when I create a new user for the module it can't access the model, because the access rule is taken for the model hr.pay_history that doesn't even exist any more.

access_hr_pay_history,access_hr_pay_history,model_hr_pay_history,,1,1,1,1

 I found a record for the old model in ir_model, but I can't delete the record. I can change user access rules from odoo and it starts working but on the next module upgrade the problem comes back.

Any way to fix this without creating a fresh instance of odoo and installing the module on it? 

Problem is that I can't delete the instance that has the problem.