This is being worked at. There is however a temporary work-around. (thanks @pumrum)
1. Force-close spotify
2. Put phone into airplane mode
3. Open spotify
4. Very quickly navigate to the search pane
5. Scroll to the bottom and click "Clear Recent Searches"
If you wait too long, Spotify will recognize that it's offline and put the Now Playing banner back at the bottom, again blocking the "Clear Recent Searches" button
Let us know if this works!