There is a peak of dust inside my lens( Canon 100-400mm 1st gen). And I can find a dot on some of my images( I have no idea why I didn't find it on other images). And is there anything that I can do to remove the dust from my lens?
As noted, dust on the front of the lens will almost never show on photos - see this famous LensRental review on Front Element Scratches
Dust on the rear element may make a slight impression - though should be simple enough to clean with a brush &/or air. Dust on the sensor will usually be cleared by the cleaning cycle.
If not, Canon [& Nikon] have a dust 'removal' algorithm that can be employed, using a reference frame for comparison.
Full instructions at Canon KB - Appending Dust Delete Data
For sake of completeness, Nikon's version is called 'Image Dust Off' - Nikon KB - How does 'Image Dust Off' work?
Dust in your lens (especially towards the front side) will likely not produce a dark spot in your image. This is more due to dust specks on the sensor, that come and go (your camera likely cleans the sensor on startup)... or stains, that tend to remain until removed by a manual sensor cleaning, but these show in every shot.
You're mistaking one bit of dust near the front of your lens for the effect of something else.
The dust on the front of your lens is not causing what you are seeing.
For more, please see these questions and their answers here at Photography SE:
See also Roger Cicala of lensrentals.com's excellent blog post, The Apocalypse of Lens Dust