Not avaiable out of the box, but you can use something like https://github.com/julianlam/nodebb-plugin-archiver or modify it to delete the topics instead of locking.
how to make a new style
how to make a new style to the forum does not reload the forum? if I do not do anything I do not change
Someone will help
@Dawid-Glomba menu --> appearance --> skins
or menu --> appearance --> custom HTML & CSS to add your own styles.
If you cannot reload, try and use your command line and enter:
is not building a new style only edition ....
@Dawid-Glomba hmmm? sorry not sure what you mean 'edition'.
There are docs on creating your own theme:https://docs.nodebb.org/en/latest/themes/create.html