Tutorial Video. Step by step below;
1
First Step
Login to your Wepwawet Control Panel

2
Second Step
Select your Server

3
Third Step
Make sure to Turn OFF the Server

4
Fourth Step
Under the General Section, Click the Files tab

5
Fifth Step
Select all the files by clicking the Checkbox near /home/container/ and click the Delete button.

6
Sixth Step
Under the Minecraft Section, Go to the Version tab and search for the version you want to install.

7
Seventh Step
Click on the Install button

8
Eighth Step
Start your Server afterward.

9
Ninth Step
Accept the EULA by pressing the I Accept button

There you go! You just reset your entire server to your preferred server software!