Make a field with broken relation editable

Are you trying to make the reference field for the relationship editable or one of the lookup fields in the relationship?

The reference field, so this was the field based on which referencing to other table was done. 

That field should still be editable. Does it have a Proxy field set for it. It so change the field properties to not use a Proxy field and it should be editable on a form.

Well, this is the screen-shot of all field's settings.
Should I change something here?

No, it�s set correctly. I�m surprised it�s not editable. So you are saying that the field has data in it, you can see records have values, but the field is not editable?

Well, this is how its look like:
 

You may want to get to Support on this one, as I would have to do some experimenting and I would not be able to to do that for a couple of days.

You might make a copy of the app and then try this in the copy

Duplicate that field or manipulate the data to get the data from your field into a new field called [ex-Loc ID input]

Change the field type on your broken field to be formula text.

Make the formula

[ex-Loc ID input]

Then change the field type back to be a text field and see if it is editable again.

To be on the same page:
1. Change type - tried
2. Making formula - tried
3. Copy app - i've made just two new tables and replicated the pattern: so created relation, deleted referenced table -> then reference filed becomes broken and uneditable.

How about if you copy the field to retain the data entry values, and then turn the current broken field into a formula field with a formula equal to the input field.

Then do all your data entity in the input field.

The formula field will still flow down to where ever it was used before.

Frankly speaking, this is the only option came to my mind so far, but I would like to check any options to keep original field open for inputs to stay transparent.
And this blocking issue is pretty odd for me, since I've expected to have an easy way to "untangle" any field from any relation and turn it to input field with the default behavior.
If you have any other ideas how to achieve this, I would be really grateful.