The operation cannot be completed: another model requires the record 
being deleted. If possible, archive it instead.  Model: Employee 
(hr.employee), Constraint: hr_employee_iwave_category_id_fkey

class HrEmployeeTag(models.Model):
    _inherit = "hr.employee"

    iwave_category_id = fields.Many2one("hr.employee.category", compute="compute_iwave_category_id", store=True,
                                        ondelete="cascade")
    category_ids = fields.Many2many(default="_get_category_ids_value")

    @api.depends('iwave_Experience')
    def compute_iwave_category_id(self):
        for rec in self:
            if rec.iwave_Experience >= 1:
                self.iwave_category_id = 1
            if rec.iwave_Experience >= 2:
                self.iwave_category_id = 2
            if rec.iwave_Experience >= 3:
                self.iwave_category_id = 3

    @api.onchange('iwave_Experience')
    def _get_category_ids_value(self):
        for rec in self:
            if rec.iwave_Experience < 1:
                rec.write({'category_ids': [6, 0, 'category_ids']})
            rec.category_ids = rec.iwave_category_id
            if rec.iwave_Experience >= 1:
                rec.write({'category_ids': [6, 0, 'category_ids']})
                rec.category_ids = rec.iwave_category_id
                if rec.iwave_Experience >= 2:
                    rec.write({'category_ids': [6, 0, 'category_ids']})
                    rec.category_ids = rec.iwave_category_id
                    if rec.iwave_Experience >= 3:
                        rec.write({'category_ids': [6, 0, 'category_ids']})
                        rec.category_ids = rec.iwave_category_id
            else:
                rec.category_ids = False

how to solve this error.