A registered retirement income fund (RRIF) is an investment account that is used to convert the savings you have in your RRSP into an income. Typically this means moving your investments, cash etc. from your RRSP into the RRIF and starting regular withdrawals. The schedule of payments to you can be arranged to meet your needs (monthly, quarterly, annual).
Prior to age 71 the formula for the minimum withdrawal from a RRIF is : 1 / (90 - age) X Account Balance.
For example, if you are 65 years of age, 90 minus 65 is 25. One over 25 is 4%. At 65, you must take out at least 4% of the RRIF balance at December 31st some time in the following calendar year. If you had $100,000 in the RRIF, you would need to take out at least $4000 the following year. After age 71, the minimum income changes and no longer follows the formula 1/(90-age) formula. At that point the the minimum income amount is predetermined by the government. You can see from the table below that as you get older, the minimum percentage increases.
Yes, you can collapse the entire account, remembering that the whole amount becomes taxable income in the year of the withdrawal or you can use the funds to purchase an annuity.