Since HTC One, doesn't support memory SD card, you need to manage your device's memory more efficient. To make more space on HTC One and get more storage by clearing out app caches, uninstalling installed apps, and managing multimedia files, do as follows:
1. Open "Settings" App
2. Tap "Storage"
3. select "Make More Space"
4. All your contents with used space are shown. You can now delete some of them to set free some memory
5. Tap "Apps" and uninstall one or many app by marking them. At the top right of the page, you see how much memory gets free