How can I upgrade from V6.14 to v7

Install / Update Setup
1 
frappe@ubuntu:~/bench-repo$ bench update
INFO:bench.utils:updating bench
Already up-to-date.
remote: Counting objects: 993, done.
remote: Compressing objects: 100% (63/63), done.
remote: Total 993 (delta 577), reused 569 (delta 556), pack-reused 374
Receiving objects: 100% (993/993), 1.15 MiB | 176.00 KiB/s, done.
Resolving deltas: 100% (755/755), completed with 248 local objects.
From https://github.com/frappe/frappe
   92a67b7..fe2c6ba  master     -> upstream/master
   536cef8..fe2c6ba  develop    -> upstream/develop
 * [new branch]      v6.x.x     -> upstream/v6.x.x
 * [new tag]         v7.0.13    -> v7.0.13
 * [new tag]         v7.0.0     -> v7.0.0
 * [new tag]         v7.0.1     -> v7.0.1
 * [new tag]         v7.0.10    -> v7.0.10
 * [new tag]         v7.0.11    -> v7.0.11
 * [new tag]         v7.0.12    -> v7.0.12
 * [new tag]         v7.0.2     -> v7.0.2
 * [new tag]         v7.0.3     -> v7.0.3
 * [new tag]         v7.0.4     -> v7.0.4
 * [new tag]         v7.0.5     -> v7.0.5
 * [new tag]         v7.0.6     -> v7.0.6
 * [new tag]         v7.0.7     -> v7.0.7
 * [new tag]         v7.0.8     -> v7.0.8
 * [new tag]         v7.0.9     -> v7.0.9

This update will cause a major version change in Frappe/ERPNext from 6 to 7.
This would take significant time to migrate and might break custom apps. Please run bench update --upgrade to confirm.

You can stay on the latest stable release by running bench switch-to-master or pin your bench to 6 by running bench switch-to-v6

Now what can I do?

2

You dont need a switch command to update your Version 6+ to Version 7.
$ bench update --upgrade
will do it for you automatically.

If you have used develop brand before and not sure if you on master branch of ERPNext and Frappe, then simple run following before upgrade, otherwise ignore.
$ bench switch-to-master

In addition, you may first look at