A res.partner record is not a customer. A res.partner record is a contact related to your business (or even your business itself) - this is also indicated by the naming of the Contacts-menu not being called 'Customers' in the first place:

A contact could be for example

• a supplier
• (a record related to) an employee
• a prospect interested in your goods
• a customer
• a contact related to any of the above (i.e. any kind of additional address)

Furthermore, a res.partner record could be everything of the above at the same time (i.e. your employee could have purchased something from your company, thus is an employee and a customer at the same time).

From a technical point of view, you can't just simply get rid of res.partner records related to a res.users record. The comment set on the res.users-model defining class Users states:

[...] res.users class now inherits from res.partner. The partner model is used to store the data related to the partner: lang, name, address, avatar, ... The user model is now dedicated to technical data.

I can't think of any logical reason why one would want to prevent the creation of res.partner records from res.users in the first place, apart from utilizing Odoo inefficiently or incorrectly.

For example, if you yon't want to have a res.partner created because they exist already, create the user from those contacts directly.

If you don't want the contacts to be created because the list of contacts would be polluted with non-customers, see Sales -> Orders -> Customers or Accounting (or Invoicing) -> Customers -> Customers. You'll find your list of contacts filtered by the field Customer Rank, indicating a contact that has received an invoice from your company (which then is actually a customer of your company).

In any case, knowing that res.users is directly related to res.partner, you may spent dozens of hours to completely rework this logic, break every single test case given by Odoo to ensure stability in the system and prepare for a massive time sink when you want to upgrade to a newer version of Odoo - or, you use filters to just see whatever you feel a customer is supposed to be defined by.

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Going to Invoicing -> Customers -> Customers list, and removing any filter, seems to show all Users and Companies in there as well.
Creating any user or company ends up showing in the above customer list.
This is the default behavior that i want to change.
I do not want users to automatically added as customers in the above customer list.

Given your comment, you want to add a domain (basically a fixed filtering) on the list view.

You should do so by extending the account module with our own module. If you haven't done this yet, you may go for an potentially not update safe way of modifying the current action. You could do so by adding a Domain Value of [('customer_rank', '>', 0)] to account.res_partner_action_customer.

For this, first enable the Developer Mode (https://www.odoo.com/documentation/18.0/applications/general/developer_mode.html). Then, navigate to Invoicing -> Customers -> Customers. Click the little Debug/Bug icon in the top right bar (next to your notifications) that appeared since you've enabled the Developer Mode and go to User Interface --> Action. In this form view, set this value to the field Domain Value:

[('customer_rank', '>', 0)]

This is not the recommended way of performing changes, but if you're unfamiliar with module development in Odoo and don't hire a developer, this is what you can do.

Above will force a base-filtering of contacts in all views using this action (i.e. also in Sales -> Customers -> Customers) by default - no matter what filter is added in the UI in addition or removed.