No need to remove the oregano flowers - but if you're harvesting your oregano, take the flowers along with the leaves - they are edible.

As for Garlic: yes, you can use bought garlic bulbs to propagate it, as long as they haven't been treated with a growth retardant. Here's how it's done.

Divide the bulbs and plant separate cloves directly in the ground in early autumn to mid-spring. Autumn plantings usually yield larger cloves. Plant about 2cm deep (deeper if winters are severe), pointed end up, and about 15cm apart. Elephant Garlic should be planted about 7-8cm deep and 30cm apart. Forcing the cloves into the soil will delay root development, so be gentle. Choose the largest cloves for the largest bulbs later. Small cloves grow into unsegmented "rounds"; these can be replanted to grow into larger bulbs with the usual count of 7-10 cloves. In warmer climates, refrigerate the bulbs for several months before planting for best results. Garlic is a heavy feeder and, to grow big bulbs, you need highly fertile soil, well supplied with all major nutrients. Full sun is best. Because high humus content and good drainage are also very important, adding compost is advisable. Garlic prefers a pH 6.0-7.0. Plant in full sun, in good light, moist but well-drained soil. Consistent soil moisture is necessary during the bulbing period, but when nearing maturity, somewhat dry soil is best. Bulbs may rot in heavy, wet soils. Keep the area around the plants clear of weeds, but be careful not to damage the shallow roots. Traditionally garlic cloves are planted on the shortest day of the year and harvested on the longest. The following summer, stop watering when the leaves turn yellow and break tops over at the base to speed up drying. After 2 to 3 weeks, when broken tops are brown and dry, carefully lift the bulbs and sun-dry them for a few days. Remove flower stalks as they appear. Garlic will tolerate frosts to Â12C for short periods. Do not grow garlic where other members of the onion family have been grown in the past 3 years.