Can males safely cease masturbation if they so desire, assuming the person isn't sexually active?
Lifelong abstainance from masterbation is completely safe. As @Noah said in his comment, there are plenty of celibate people out there with no adverse health from their life choice.
Even though sperm is constantly being produced, dead sperm will be shed after time anyway. See my answer to a similar question at Effects of masturbation on Health.
I have also seen this good answer from @Narusan at How many times a week is masturbating good for health? which mentions that there is no defined amount which is healthy or unhealthy. It is down to individual choice and health.
-- Edit to answer queries in the comments --
@user8840 questioned this answer in the comments. He/she said,
How about "blue balls", "the condition of temporary fluid congestion in the testicles accompanied by testicular pain"
I agree with what @ShadowWizard said, which was that
this only applies when you're sexually aroused for long period of time. I am pretty sure this answer assumes no sexual arousal is involved.
I would like to stress on some of the points surrounding this "condition", and some of these points are mentioned in the Wikipedia article linked above.
Vasocongestion, (temporary fluid congestion) as mentioned in the link provided in the Wikipedia article, is required for erection in men and clitoral arousal in women. It is the increase in blood and pressure in the relevant body parts.
Blue balls is a slang term and has no official term which I have been able to find. The Wikipedia article says that some urologists call it epididymal hypertension, however, researching a bit more, one article in the journal Pediatrics, published in 2000, discussed "epididymal hypertension" as a potential diagnosis in young adult males. The problem is that "epididymal hypertension" is a diagnosis which is a general, all encompasing diagnosis for all sorts of causes of testicular pain.
The condition described, what the urologists often term “epididymal hypertension,” and some have labeled “deadly sperm buildup” or “DSB,” has many other manifestations of which physicians and their caretakers ought to be aware. (Rockney & Alario, 2001)
another article states the fact that
The medical community hasn't spent a ton of time on this particular phenomenon. For one thing, it is absolutely non life-threatening, despite the belief otherwise by many a first time sufferer. Plus, any topic even suggesting sexuality among the sub voting aged crowd is politically charged and uncomfortable for many healthcare providers to broach with either their patients or their patients' parents (especially the moms).
Worse yet, the immediate relief of the pain is most efficiently handled by the immediate release of the arousal. The easiest way to do this, of course, is through orgasm.
- Boys and men will often wake up with an erection in the morning, with or without stimulation or erotic dreams. These erections are sometimes referred to as "morning wood" or "morning glory".
Whether the erection was nocturnal or not, the easiest (and quickest) treatment for this is ejaculation. However, even without release, the condition will subside on its own within an hour or two, although it can be within minutes. Although rare, epididymal hypertension could last as long as 24 hours.