Removable protective cap?
The cap protects your drink and the spout from impurities during transport or your dirtiest activities.
If you don't need it, feel free to remove it to make the bottle easier to use.
Cleaning your water bottle
Clean bottle well after every use. If you use isotonic drinks, rinse all parts thoroughly, including the bottle, top and cap to ensure no liquid remains. Use liquid soap and a long brush to clean the bottom of the bottle well.
Leave to completely dry and store without the top so that the bottle can air out. If not, mould may grow in the bottle.
Not dishwasher safe (especially at temps over 70°C).