DRF_Template/backend/accounts/admin.py

from django import forms
from django.contrib import admin
from django.contrib.auth.admin import UserAdmin
from .models import CustomUser


class CustomUserAdmin(UserAdmin):
    model = CustomUser
    list_display = ('id', 'is_active', 'user_group',) + UserAdmin.list_display
    # Editable fields per instance
    fieldsets = UserAdmin.fieldsets + (
        (None, {'fields': ('avatar',)}),
    )


admin.site.register(CustomUser, CustomUserAdmin)