How to update the treeview serial number after deleting the items

Question

I tried this code but when an item is deleted the serial no doesn't get updated. I want this program delete the data and update the serial number after deletion. I tried to initiate a variable but it gets updated to 1 every time I click add data button.

from tkinter import *
from tkinter import ttk

# Create an instance of tkinter frame
win = Tk()

# Set the size of the tkinter window
win.geometry("700x350")

# Create an instance of Style widget
style = ttk.Style()
style.theme_use('clam')

# Add a Treeview widget
tree = ttk.Treeview(win, column=("c1", "c2"), show='headings', height=8)
tree.column("# 1", anchor=CENTER)
tree.heading("# 1", text="ID")
tree.column("# 2", anchor=CENTER)
tree.heading("# 2", text="Company")

# Insert the data in Treeview widget
tree.insert('', 'end', text="1", values=('1', 'Honda'))
tree.insert('', 'end', text="2", values=('2', 'Hyundai'))
tree.insert('', 'end', text="3", values=('3', 'Tesla'))
tree.insert('', 'end', text="4", values=('4', 'Wolkswagon'))
tree.insert('', 'end', text="5", values=('5', 'Tata Motors'))
tree.insert('', 'end', text="6", values=('6', 'Renault'))

tree.pack()

def edit():
   # Get selected item to Edit
   selected_item = tree.selection()[0]
   tree.item(selected_item, text="blub", values=("foo", "bar"))

def delete():
   # Get selected item to Delete
   selected_item = tree.selection()[0]
   tree.delete(selected_item)

# Add Buttons to Edit and Delete the Treeview items
edit_btn = ttk.Button(win, text="Edit", command=edit)
edit_btn.pack()
del_btn = ttk.Button(win, text="Delete", command=delete)
del_btn.pack()

win.mainloop()

So I have tried this snippet:

def delete_data():
    global i
    if tree.selection():
        selected_item = tree.selection()[0]
        tree.delete(selected_item)
        i=i-1