I hope you are well today.
> I don’t want them to show the message ” you get free delivery”.
If you don’t want to show the massage, in the plugin’s settings, go to the General section and set the General Options > Message on free shipping reached field empty. It will disable the feature.
> I tries manual minim amount but nothing happen.
If you had tried with the Manual min amount, then it should have worked. Please ensure that you have set the 4 zone values to -1.
However, If the problem persists, would it be possible for you to share your WordPress dashboard access so we can take a look for you? You can send your details to [email protected]