UFW wont delete rule

I was testing something and added a rule to my firewall to allow port 9000. in retrospect, I should have just disabled it temporarily. anyhow, I went to remove the rule and it wont let me, it says rule not found.

$ sudo ufw delete 9000
ERROR: Could not find rule '9000'

but clearly, the rule is still active:

$ sudo ufw status verbose
Status: active
Logging: on (low)
Default: deny (incoming), allow (outgoing), disabled (routed)
New profiles: skip

To                         Action      From
--                         ------      ----
80                         ALLOW IN    Anywhere
443                        ALLOW IN    Anywhere
9000                       ALLOW IN    Anywhere
80 (v6)                    ALLOW IN    Anywhere (v6)
443 (v6)                   ALLOW IN    Anywhere (v6)
9000 (v6)                  ALLOW IN    Anywhere (v6)

I read the UFW help and it says you can delete a port number, but it doesn't happen. How can I remove the rule for port 9000 from UFW?

The correct syntax would be:

sudo ufw delete allow 9000

If you make a rule by the following:

sudo ufw allow 9000

Then the rule is allow 9000. Now if you want to delete the rule:

sudo ufw delete rule

i.e.

sudo ufw delete allow 9000

The first step you can list all current rules by number:

$ sudo ufw status numbered

Then base on the listed numbers, you can delete rule by number. The number of the rule is shown in the leftmost column.

$ sudo ufw delete 2

You can refer to link: https://www.digitalocean.com/community/tutorials/how-to-set-up-a-firewall-with-ufw-on-ubuntu-14-04