The best way to do this depends on whether you want to turn it off for a specific area of text or the whole document.
If it just for a specific area, e.g. paragraph, then highlight the text, go to the Text menu and select “Language and Hyphenation”:
Then tick the “Don’t hyphenate here” option.
If you want to change this for the whole document, or future documents, you can set this option against the Style you use for your text. You can see how to do this in the topic “Setting up double space and no text break at end of line”.
This functionality is handled by the Papyrus Author macros. You can find them under the Options menu.
You can delete macros, but you can also edit them and change the shortcut keys used so you can retain the functionality.